diff --git a/.changeset/modern-brooms-rule.md b/.changeset/modern-brooms-rule.md
new file mode 100644
index 0000000000..ecc2abe9f9
--- /dev/null
+++ b/.changeset/modern-brooms-rule.md
@@ -0,0 +1,25 @@
+---
+"@latticexyz/cli": patch
+"@latticexyz/world-modules": patch
+"@latticexyz/world": major
+---
+
+Previously `registerSystem` and `registerTable` had a side effect of registering namespaces if the system or table's namespace didn't exist yet.
+This caused a possible frontrunning issue, where an attacker could detect a `registerSystem`/`registerTable` transaction in the mempool,
+insert a `registerNamespace` transaction before it, grant themselves access to the namespace, transfer ownership of the namespace to the victim,
+so that the `registerSystem`/`registerTable` transactions still went through successfully.
+To mitigate this issue, the side effect of registering a namespace in `registerSystem` and `registerTable` has been removed.
+Calls to these functions now expect the respective namespace to exist and the caller to own the namespace, otherwise they revert.
+
+Changes in consuming projects are only necessary if tables or systems are registered manually.
+If only the MUD deployer is used to register tables and systems, no changes are necessary, as the MUD deployer has been updated accordingly.
+
+```diff
++  world.registerNamespace(namespaceId);
+   world.registerSystem(systemId, system, true);
+```
+
+```diff
++  world.registerNamespace(namespaceId);
+   MyTable.register();
+```
diff --git a/examples/minimal/packages/contracts/script/PostDeploy.s.sol b/examples/minimal/packages/contracts/script/PostDeploy.s.sol
index 22fd9d5f19..661a15ba47 100644
--- a/examples/minimal/packages/contracts/script/PostDeploy.s.sol
+++ b/examples/minimal/packages/contracts/script/PostDeploy.s.sol
@@ -4,7 +4,7 @@ pragma solidity >=0.8.21;
 import { Script } from "forge-std/Script.sol";
 import { console } from "forge-std/console.sol";
 import { StoreSwitch } from "@latticexyz/store/src/StoreSwitch.sol";
-import { ResourceId, WorldResourceIdLib } from "@latticexyz/world/src/WorldResourceId.sol";
+import { ResourceId, WorldResourceIdLib, WorldResourceIdInstance } from "@latticexyz/world/src/WorldResourceId.sol";
 import { RESOURCE_SYSTEM } from "@latticexyz/world/src/worldResourceTypes.sol";
 
 import { MessageTable, MessageTableTableId } from "../src/codegen/index.sol";
@@ -12,6 +12,8 @@ import { IWorld } from "../src/codegen/world/IWorld.sol";
 import { ChatNamespacedSystem } from "../src/systems/ChatNamespacedSystem.sol";
 
 contract PostDeploy is Script {
+  using WorldResourceIdInstance for ResourceId;
+
   function run(address worldAddress) external {
     // Specify a store so that you can use tables directly in PostDeploy
     StoreSwitch.setStoreAddress(worldAddress);
@@ -29,8 +31,10 @@ contract PostDeploy is Script {
       namespace: "namespace",
       name: "ChatNamespaced"
     });
+    IWorld(worldAddress).registerNamespace(systemId.getNamespaceId());
     IWorld(worldAddress).registerSystem(systemId, chatNamespacedSystem, true);
     IWorld(worldAddress).registerFunctionSelector(systemId, "sendMessage(string)");
+
     // Grant this system access to MessageTable
     IWorld(worldAddress).grantAccess(MessageTableTableId, address(chatNamespacedSystem));
 
diff --git a/packages/cli/src/deploy/assertNamespaceOwner.ts b/packages/cli/src/deploy/assertNamespaceOwner.ts
deleted file mode 100644
index 4ed1e15c81..0000000000
--- a/packages/cli/src/deploy/assertNamespaceOwner.ts
+++ /dev/null
@@ -1,42 +0,0 @@
-import { Account, Chain, Client, Hex, Transport, getAddress } from "viem";
-import { WorldDeploy, worldTables } from "./common";
-import { hexToResource, resourceToHex } from "@latticexyz/common";
-import { getResourceIds } from "./getResourceIds";
-import { getTableValue } from "./getTableValue";
-
-export async function assertNamespaceOwner({
-  client,
-  worldDeploy,
-  resourceIds,
-}: {
-  readonly client: Client<Transport, Chain | undefined, Account>;
-  readonly worldDeploy: WorldDeploy;
-  readonly resourceIds: readonly Hex[];
-}): Promise<void> {
-  const desiredNamespaces = Array.from(new Set(resourceIds.map((resourceId) => hexToResource(resourceId).namespace)));
-  const existingResourceIds = await getResourceIds({ client, worldDeploy });
-  const existingNamespaces = Array.from(
-    new Set(existingResourceIds.map((resourceId) => hexToResource(resourceId).namespace))
-  );
-
-  const namespaces = desiredNamespaces.filter((namespace) => existingNamespaces.includes(namespace));
-  const namespaceOwners = await Promise.all(
-    namespaces.map(async (namespace) => {
-      const { owner } = await getTableValue({
-        client,
-        worldDeploy,
-        table: worldTables.world_NamespaceOwner,
-        key: { namespaceId: resourceToHex({ type: "namespace", namespace, name: "" }) },
-      });
-      return [namespace, owner];
-    })
-  );
-
-  const unauthorizedNamespaces = namespaceOwners
-    .filter(([, owner]) => getAddress(owner) !== getAddress(client.account.address))
-    .map(([namespace]) => namespace);
-
-  if (unauthorizedNamespaces.length) {
-    throw new Error(`You are attempting to deploy to namespaces you do not own: ${unauthorizedNamespaces.join(", ")}`);
-  }
-}
diff --git a/packages/cli/src/deploy/deploy.ts b/packages/cli/src/deploy/deploy.ts
index b75c189ed7..0973392c9b 100644
--- a/packages/cli/src/deploy/deploy.ts
+++ b/packages/cli/src/deploy/deploy.ts
@@ -9,12 +9,12 @@ import { getWorldDeploy } from "./getWorldDeploy";
 import { ensureFunctions } from "./ensureFunctions";
 import { ensureModules } from "./ensureModules";
 import { Table } from "./configToTables";
-import { assertNamespaceOwner } from "./assertNamespaceOwner";
+import { ensureNamespaceOwner } from "./ensureNamespaceOwner";
 import { debug } from "./debug";
 import { resourceLabel } from "./resourceLabel";
 import { uniqueBy } from "@latticexyz/common/utils";
 import { ensureContractsDeployed } from "./ensureContractsDeployed";
-import { coreModuleBytecode, worldFactoryBytecode, worldFactoryContracts } from "./ensureWorldFactory";
+import { worldFactoryContracts } from "./ensureWorldFactory";
 
 type DeployOptions<configInput extends ConfigInput> = {
   client: Client<Transport, Chain | undefined, Account>;
@@ -67,12 +67,17 @@ export async function deploy<configInput extends ConfigInput>({
     throw new Error(`Unsupported World version: ${worldDeploy.worldVersion}`);
   }
 
-  await assertNamespaceOwner({
+  const namespaceTxs = await ensureNamespaceOwner({
     client,
     worldDeploy,
     resourceIds: [...tables.map((table) => table.tableId), ...systems.map((system) => system.systemId)],
   });
 
+  debug("waiting for all namespace registration transactions to confirm");
+  for (const tx of namespaceTxs) {
+    await waitForTransactionReceipt(client, { hash: tx });
+  }
+
   const tableTxs = await ensureTables({
     client,
     worldDeploy,
diff --git a/packages/cli/src/deploy/ensureNamespaceOwner.ts b/packages/cli/src/deploy/ensureNamespaceOwner.ts
new file mode 100644
index 0000000000..65384d2de3
--- /dev/null
+++ b/packages/cli/src/deploy/ensureNamespaceOwner.ts
@@ -0,0 +1,71 @@
+import { Account, Chain, Client, Hex, Transport, getAddress } from "viem";
+import { WorldDeploy, worldAbi, worldTables } from "./common";
+import { hexToResource, resourceToHex, writeContract } from "@latticexyz/common";
+import { getResourceIds } from "./getResourceIds";
+import { getTableValue } from "./getTableValue";
+import { debug } from "./debug";
+
+export async function ensureNamespaceOwner({
+  client,
+  worldDeploy,
+  resourceIds,
+}: {
+  readonly client: Client<Transport, Chain | undefined, Account>;
+  readonly worldDeploy: WorldDeploy;
+  readonly resourceIds: readonly Hex[];
+}): Promise<readonly Hex[]> {
+  const desiredNamespaces = Array.from(new Set(resourceIds.map((resourceId) => hexToResource(resourceId).namespace)));
+  const existingResourceIds = await getResourceIds({ client, worldDeploy });
+  const existingNamespaces = new Set(existingResourceIds.map((resourceId) => hexToResource(resourceId).namespace));
+  if (existingNamespaces.size) {
+    debug(
+      "found",
+      existingNamespaces.size,
+      "existing namespaces:",
+      Array.from(existingNamespaces)
+        .map((namespace) => (namespace === "" ? "<root>" : namespace))
+        .join(", ")
+    );
+  }
+
+  // Assert ownership of existing namespaces
+  const existingDesiredNamespaces = desiredNamespaces.filter((namespace) => existingNamespaces.has(namespace));
+  const namespaceOwners = await Promise.all(
+    existingDesiredNamespaces.map(async (namespace) => {
+      const { owner } = await getTableValue({
+        client,
+        worldDeploy,
+        table: worldTables.world_NamespaceOwner,
+        key: { namespaceId: resourceToHex({ type: "namespace", namespace, name: "" }) },
+      });
+      return [namespace, owner];
+    })
+  );
+
+  const unauthorizedNamespaces = namespaceOwners
+    .filter(([, owner]) => getAddress(owner) !== getAddress(client.account.address))
+    .map(([namespace]) => namespace);
+
+  if (unauthorizedNamespaces.length) {
+    throw new Error(`You are attempting to deploy to namespaces you do not own: ${unauthorizedNamespaces.join(", ")}`);
+  }
+
+  // Register missing namespaces
+  const missingNamespaces = desiredNamespaces.filter((namespace) => !existingNamespaces.has(namespace));
+  if (missingNamespaces.length > 0) {
+    debug("registering namespaces", Array.from(missingNamespaces).join(", "));
+  }
+  const registrationTxs = Promise.all(
+    missingNamespaces.map((namespace) =>
+      writeContract(client, {
+        chain: client.chain ?? null,
+        address: worldDeploy.address,
+        abi: worldAbi,
+        functionName: "registerNamespace",
+        args: [resourceToHex({ namespace, type: "namespace", name: "" })],
+      })
+    )
+  );
+
+  return registrationTxs;
+}
diff --git a/packages/world-modules/gas-report.json b/packages/world-modules/gas-report.json
index 2e39630ee8..87d1a9b1d4 100644
--- a/packages/world-modules/gas-report.json
+++ b/packages/world-modules/gas-report.json
@@ -75,13 +75,13 @@
     "file": "test/KeysInTableModule.t.sol",
     "test": "testInstallComposite",
     "name": "install keys in table module",
-    "gasUsed": 1413179
+    "gasUsed": 1413282
   },
   {
     "file": "test/KeysInTableModule.t.sol",
     "test": "testInstallGas",
     "name": "install keys in table module",
-    "gasUsed": 1413179
+    "gasUsed": 1413282
   },
   {
     "file": "test/KeysInTableModule.t.sol",
@@ -93,13 +93,13 @@
     "file": "test/KeysInTableModule.t.sol",
     "test": "testInstallSingleton",
     "name": "install keys in table module",
-    "gasUsed": 1413179
+    "gasUsed": 1413282
   },
   {
     "file": "test/KeysInTableModule.t.sol",
     "test": "testSetAndDeleteRecordHookCompositeGas",
     "name": "install keys in table module",
-    "gasUsed": 1413179
+    "gasUsed": 1413282
   },
   {
     "file": "test/KeysInTableModule.t.sol",
@@ -117,7 +117,7 @@
     "file": "test/KeysInTableModule.t.sol",
     "test": "testSetAndDeleteRecordHookGas",
     "name": "install keys in table module",
-    "gasUsed": 1413179
+    "gasUsed": 1413282
   },
   {
     "file": "test/KeysInTableModule.t.sol",
@@ -135,7 +135,7 @@
     "file": "test/KeysWithValueModule.t.sol",
     "test": "testGetKeysWithValueGas",
     "name": "install keys with value module",
-    "gasUsed": 653541
+    "gasUsed": 668083
   },
   {
     "file": "test/KeysWithValueModule.t.sol",
@@ -153,7 +153,7 @@
     "file": "test/KeysWithValueModule.t.sol",
     "test": "testInstall",
     "name": "install keys with value module",
-    "gasUsed": 653541
+    "gasUsed": 668083
   },
   {
     "file": "test/KeysWithValueModule.t.sol",
@@ -165,7 +165,7 @@
     "file": "test/KeysWithValueModule.t.sol",
     "test": "testSetAndDeleteRecordHook",
     "name": "install keys with value module",
-    "gasUsed": 653541
+    "gasUsed": 668083
   },
   {
     "file": "test/KeysWithValueModule.t.sol",
@@ -183,7 +183,7 @@
     "file": "test/KeysWithValueModule.t.sol",
     "test": "testSetField",
     "name": "install keys with value module",
-    "gasUsed": 653541
+    "gasUsed": 668083
   },
   {
     "file": "test/KeysWithValueModule.t.sol",
@@ -267,7 +267,7 @@
     "file": "test/StandardDelegationsModule.t.sol",
     "test": "testCallFromCallboundDelegation",
     "name": "register a callbound delegation",
-    "gasUsed": 118325
+    "gasUsed": 118319
   },
   {
     "file": "test/StandardDelegationsModule.t.sol",
@@ -279,7 +279,7 @@
     "file": "test/StandardDelegationsModule.t.sol",
     "test": "testCallFromSystemDelegation",
     "name": "register a systembound delegation",
-    "gasUsed": 115881
+    "gasUsed": 115875
   },
   {
     "file": "test/StandardDelegationsModule.t.sol",
@@ -291,7 +291,7 @@
     "file": "test/StandardDelegationsModule.t.sol",
     "test": "testCallFromTimeboundDelegation",
     "name": "register a timebound delegation",
-    "gasUsed": 112819
+    "gasUsed": 112813
   },
   {
     "file": "test/StandardDelegationsModule.t.sol",
@@ -303,7 +303,7 @@
     "file": "test/UniqueEntityModule.t.sol",
     "test": "testInstall",
     "name": "install unique entity module",
-    "gasUsed": 681852
+    "gasUsed": 694780
   },
   {
     "file": "test/UniqueEntityModule.t.sol",
@@ -315,7 +315,7 @@
     "file": "test/UniqueEntityModule.t.sol",
     "test": "testInstallRoot",
     "name": "installRoot unique entity module",
-    "gasUsed": 648249
+    "gasUsed": 663774
   },
   {
     "file": "test/UniqueEntityModule.t.sol",
diff --git a/packages/world-modules/src/modules/erc20-puppet/ERC20Module.sol b/packages/world-modules/src/modules/erc20-puppet/ERC20Module.sol
index 5a65cd5af5..7a5459f2cb 100644
--- a/packages/world-modules/src/modules/erc20-puppet/ERC20Module.sol
+++ b/packages/world-modules/src/modules/erc20-puppet/ERC20Module.sol
@@ -6,6 +6,7 @@ import { ResourceId } from "@latticexyz/store/src/ResourceId.sol";
 import { Module } from "@latticexyz/world/src/Module.sol";
 import { WorldResourceIdLib } from "@latticexyz/world/src/WorldResourceId.sol";
 import { IBaseWorld } from "@latticexyz/world/src/codegen/interfaces/IBaseWorld.sol";
+import { revertWithBytes } from "@latticexyz/world/src/revertWithBytes.sol";
 
 import { Puppet } from "../puppet/Puppet.sol";
 import { createPuppet } from "../puppet/createPuppet.sol";
@@ -53,7 +54,10 @@ contract ERC20Module is Module {
 
     // Register the ERC20 tables and system
     IBaseWorld world = IBaseWorld(_world());
-    registrationLibrary.delegatecall(abi.encodeCall(ERC20ModuleRegistrationLibrary.register, (world, namespace)));
+    (bool success, bytes memory returnData) = registrationLibrary.delegatecall(
+      abi.encodeCall(ERC20ModuleRegistrationLibrary.register, (world, namespace))
+    );
+    if (!success) revertWithBytes(returnData);
 
     // Initialize the Metadata
     ERC20Metadata.set(_metadataTableId(namespace), metadata);
@@ -68,6 +72,7 @@ contract ERC20Module is Module {
 
     // Register the ERC20 in the ERC20Registry
     if (!ResourceIds.getExists(ERC20_REGISTRY_TABLE_ID)) {
+      world.registerNamespace(MODULE_NAMESPACE_ID);
       ERC20Registry.register(ERC20_REGISTRY_TABLE_ID);
     }
     ERC20Registry.set(ERC20_REGISTRY_TABLE_ID, namespaceId, puppet);
@@ -83,6 +88,12 @@ contract ERC20ModuleRegistrationLibrary {
    * Register systems and tables for a new ERC20 token in a given namespace
    */
   function register(IBaseWorld world, bytes14 namespace) public {
+    // Register the namespace if it doesn't exist yet
+    ResourceId tokenNamespace = WorldResourceIdLib.encodeNamespace(namespace);
+    if (!ResourceIds.getExists(tokenNamespace)) {
+      world.registerNamespace(tokenNamespace);
+    }
+
     // Register the tables
     Allowances.register(_allowancesTableId(namespace));
     Balances.register(_balancesTableId(namespace));
diff --git a/packages/world-modules/src/modules/erc721-puppet/ERC721Module.sol b/packages/world-modules/src/modules/erc721-puppet/ERC721Module.sol
index 6a297e05cd..b96caea949 100644
--- a/packages/world-modules/src/modules/erc721-puppet/ERC721Module.sol
+++ b/packages/world-modules/src/modules/erc721-puppet/ERC721Module.sol
@@ -7,6 +7,7 @@ import { Module } from "@latticexyz/world/src/Module.sol";
 import { WorldResourceIdLib } from "@latticexyz/world/src/WorldResourceId.sol";
 import { IBaseWorld } from "@latticexyz/world/src/codegen/interfaces/IBaseWorld.sol";
 import { InstalledModules } from "@latticexyz/world/src/codegen/tables/InstalledModules.sol";
+import { revertWithBytes } from "@latticexyz/world/src/revertWithBytes.sol";
 
 import { Puppet } from "../puppet/Puppet.sol";
 import { createPuppet } from "../puppet/createPuppet.sol";
@@ -57,7 +58,10 @@ contract ERC721Module is Module {
 
     // Register the ERC721 tables and system
     IBaseWorld world = IBaseWorld(_world());
-    registrationLibrary.delegatecall(abi.encodeCall(ERC721ModuleRegistrationLibrary.register, (world, namespace)));
+    (bool success, bytes memory returnData) = registrationLibrary.delegatecall(
+      abi.encodeCall(ERC721ModuleRegistrationLibrary.register, (world, namespace))
+    );
+    if (!success) revertWithBytes(returnData);
 
     // Initialize the Metadata
     ERC721Metadata.set(_metadataTableId(namespace), metadata);
@@ -72,6 +76,7 @@ contract ERC721Module is Module {
 
     // Register the ERC721 in the ERC20Registry
     if (!ResourceIds.getExists(ERC721_REGISTRY_TABLE_ID)) {
+      world.registerNamespace(MODULE_NAMESPACE_ID);
       ERC721Registry.register(ERC721_REGISTRY_TABLE_ID);
     }
     ERC721Registry.set(ERC721_REGISTRY_TABLE_ID, namespaceId, puppet);
@@ -87,8 +92,13 @@ contract ERC721ModuleRegistrationLibrary {
    * Register systems and tables for a new ERC721 token in a given namespace
    */
   function register(IBaseWorld world, bytes14 namespace) public {
-    // Register the tables
+    // Register the namespace if it doesn't exist yet
+    ResourceId tokenNamespace = WorldResourceIdLib.encodeNamespace(namespace);
+    if (!ResourceIds.getExists(tokenNamespace)) {
+      world.registerNamespace(tokenNamespace);
+    }
 
+    // Register the tables
     OperatorApproval.register(_operatorApprovalTableId(namespace));
     Owners.register(_ownersTableId(namespace));
     TokenApproval.register(_tokenApprovalTableId(namespace));
diff --git a/packages/world-modules/src/modules/keyswithvalue/KeysWithValueModule.sol b/packages/world-modules/src/modules/keyswithvalue/KeysWithValueModule.sol
index 7ca3362bba..cdfdcab433 100644
--- a/packages/world-modules/src/modules/keyswithvalue/KeysWithValueModule.sol
+++ b/packages/world-modules/src/modules/keyswithvalue/KeysWithValueModule.sol
@@ -2,8 +2,9 @@
 pragma solidity >=0.8.21;
 import { StoreSwitch } from "@latticexyz/store/src/StoreSwitch.sol";
 import { BEFORE_SET_RECORD, BEFORE_SPLICE_STATIC_DATA, AFTER_SPLICE_STATIC_DATA, BEFORE_SPLICE_DYNAMIC_DATA, AFTER_SPLICE_DYNAMIC_DATA, BEFORE_DELETE_RECORD } from "@latticexyz/store/src/storeHookTypes.sol";
-import { Module } from "@latticexyz/world/src/Module.sol";
+import { ResourceIds } from "@latticexyz/store/src/codegen/tables/ResourceIds.sol";
 
+import { Module } from "@latticexyz/world/src/Module.sol";
 import { IBaseWorld } from "@latticexyz/world/src/codegen/interfaces/IBaseWorld.sol";
 import { InstalledModules } from "@latticexyz/world/src/codegen/index.sol";
 
@@ -45,16 +46,24 @@ contract KeysWithValueModule is Module {
 
     // Extract source table id from args
     ResourceId sourceTableId = ResourceId.wrap(abi.decode(args, (bytes32)));
-    ResourceId targetTableSelector = getTargetTableId(MODULE_NAMESPACE, sourceTableId);
+    ResourceId targetTableId = getTargetTableId(MODULE_NAMESPACE, sourceTableId);
 
     IBaseWorld world = IBaseWorld(_world());
 
+    // Register the target namespace if it doesn't exist yet
+    if (!ResourceIds.getExists(targetTableId.getNamespaceId())) {
+      (bool registrationSuccess, bytes memory registrationReturnData) = address(world).delegatecall(
+        abi.encodeCall(world.registerNamespace, (targetTableId.getNamespaceId()))
+      );
+      if (!registrationSuccess) revertWithBytes(registrationReturnData);
+    }
+
     // Register the target table
     (bool success, bytes memory returnData) = address(world).delegatecall(
       abi.encodeCall(
         world.registerTable,
         (
-          targetTableSelector,
+          targetTableId,
           KeysWithValue.getFieldLayout(),
           KeysWithValue.getKeySchema(),
           KeysWithValue.getValueSchema(),
@@ -64,9 +73,11 @@ contract KeysWithValueModule is Module {
       )
     );
 
+    if (!success) revertWithBytes(returnData);
+
     // Grant the hook access to the target table
     (success, returnData) = address(world).delegatecall(
-      abi.encodeCall(world.grantAccess, (targetTableSelector, address(hook)))
+      abi.encodeCall(world.grantAccess, (targetTableId, address(hook)))
     );
 
     if (!success) revertWithBytes(returnData);
diff --git a/packages/world-modules/src/modules/puppet/PuppetModule.sol b/packages/world-modules/src/modules/puppet/PuppetModule.sol
index ecf4fcfad4..2b5ec19d9c 100644
--- a/packages/world-modules/src/modules/puppet/PuppetModule.sol
+++ b/packages/world-modules/src/modules/puppet/PuppetModule.sol
@@ -2,13 +2,15 @@
 pragma solidity >=0.8.21;
 
 import { IBaseWorld } from "@latticexyz/world/src/codegen/interfaces/IBaseWorld.sol";
-
 import { Module } from "@latticexyz/world/src/Module.sol";
 import { revertWithBytes } from "@latticexyz/world/src/revertWithBytes.sol";
+import { WorldResourceIdInstance } from "@latticexyz/world/src/WorldResourceId.sol";
+
+import { ResourceId } from "@latticexyz/store/src/ResourceId.sol";
 
 import { PuppetFactorySystem } from "./PuppetFactorySystem.sol";
 import { PuppetDelegationControl } from "./PuppetDelegationControl.sol";
-import { MODULE_NAME, PUPPET_DELEGATION, PUPPET_FACTORY, PUPPET_TABLE_ID } from "./constants.sol";
+import { MODULE_NAME, PUPPET_DELEGATION, PUPPET_FACTORY, PUPPET_TABLE_ID, NAMESPACE_ID } from "./constants.sol";
 
 import { PuppetRegistry } from "./tables/PuppetRegistry.sol";
 
@@ -16,6 +18,8 @@ import { PuppetRegistry } from "./tables/PuppetRegistry.sol";
  * This module registers tables and delegation control systems required for puppet delegations
  */
 contract PuppetModule is Module {
+  using WorldResourceIdInstance for ResourceId;
+
   PuppetDelegationControl private immutable puppetDelegationControl = new PuppetDelegationControl();
   PuppetFactorySystem private immutable puppetFactorySystem = new PuppetFactorySystem();
 
@@ -26,11 +30,23 @@ contract PuppetModule is Module {
   function installRoot(bytes memory) public {
     IBaseWorld world = IBaseWorld(_world());
 
+    // Register namespace
+    (bool success, bytes memory returnData) = address(world).delegatecall(
+      abi.encodeCall(world.registerNamespace, (NAMESPACE_ID))
+    );
+    if (!success) revertWithBytes(returnData);
+
     // Register table
     PuppetRegistry.register(PUPPET_TABLE_ID);
 
-    // Register system
-    (bool success, bytes memory returnData) = address(world).delegatecall(
+    // Register puppet factory
+    (success, returnData) = address(world).delegatecall(
+      abi.encodeCall(world.registerSystem, (PUPPET_FACTORY, puppetFactorySystem, true))
+    );
+    if (!success) revertWithBytes(returnData);
+
+    // Register puppet delegation control
+    (success, returnData) = address(world).delegatecall(
       abi.encodeCall(world.registerSystem, (PUPPET_DELEGATION, puppetDelegationControl, true))
     );
     if (!success) revertWithBytes(returnData);
@@ -39,6 +55,9 @@ contract PuppetModule is Module {
   function install(bytes memory) public {
     IBaseWorld world = IBaseWorld(_world());
 
+    // Register namespace
+    world.registerNamespace(NAMESPACE_ID);
+
     // Register table
     PuppetRegistry.register(PUPPET_TABLE_ID);
 
diff --git a/packages/world-modules/src/modules/puppet/constants.sol b/packages/world-modules/src/modules/puppet/constants.sol
index c441dd03b9..88efb01632 100644
--- a/packages/world-modules/src/modules/puppet/constants.sol
+++ b/packages/world-modules/src/modules/puppet/constants.sol
@@ -3,12 +3,14 @@ pragma solidity >=0.8.21;
 
 import { ResourceId } from "@latticexyz/store/src/ResourceId.sol";
 import { RESOURCE_TABLE } from "@latticexyz/store/src/storeResourceTypes.sol";
-import { RESOURCE_SYSTEM } from "@latticexyz/world/src/worldResourceTypes.sol";
+import { RESOURCE_SYSTEM, RESOURCE_NAMESPACE } from "@latticexyz/world/src/worldResourceTypes.sol";
 import { ROOT_NAMESPACE } from "@latticexyz/world/src/constants.sol";
 
 bytes16 constant MODULE_NAME = bytes16("puppet");
 bytes14 constant NAMESPACE = bytes14("puppet");
 
+ResourceId constant NAMESPACE_ID = ResourceId.wrap(bytes32(abi.encodePacked(RESOURCE_NAMESPACE, NAMESPACE)));
+
 ResourceId constant PUPPET_DELEGATION = ResourceId.wrap(
   bytes32(abi.encodePacked(RESOURCE_SYSTEM, NAMESPACE, bytes16("Delegation")))
 );
diff --git a/packages/world-modules/src/modules/uniqueentity/UniqueEntityModule.sol b/packages/world-modules/src/modules/uniqueentity/UniqueEntityModule.sol
index 36ddb01e8a..1ba3c0f3f4 100644
--- a/packages/world-modules/src/modules/uniqueentity/UniqueEntityModule.sol
+++ b/packages/world-modules/src/modules/uniqueentity/UniqueEntityModule.sol
@@ -11,7 +11,7 @@ import { revertWithBytes } from "@latticexyz/world/src/revertWithBytes.sol";
 import { UniqueEntity } from "./tables/UniqueEntity.sol";
 import { UniqueEntitySystem } from "./UniqueEntitySystem.sol";
 
-import { MODULE_NAME, TABLE_ID, SYSTEM_ID } from "./constants.sol";
+import { MODULE_NAME, TABLE_ID, SYSTEM_ID, NAMESPACE_ID } from "./constants.sol";
 
 /**
  * This module creates a table that stores a nonce, and
@@ -33,11 +33,17 @@ contract UniqueEntityModule is Module {
 
     IBaseWorld world = IBaseWorld(_world());
 
+    // Register namespace
+    (bool success, bytes memory data) = address(world).delegatecall(
+      abi.encodeCall(world.registerNamespace, (NAMESPACE_ID))
+    );
+    if (!success) revertWithBytes(data);
+
     // Register table
     UniqueEntity._register(TABLE_ID);
 
     // Register system
-    (bool success, bytes memory data) = address(world).delegatecall(
+    (success, data) = address(world).delegatecall(
       abi.encodeCall(world.registerSystem, (SYSTEM_ID, uniqueEntitySystem, true))
     );
     if (!success) revertWithBytes(data);
@@ -56,6 +62,9 @@ contract UniqueEntityModule is Module {
 
     IBaseWorld world = IBaseWorld(_world());
 
+    // Register namespace
+    world.registerNamespace(NAMESPACE_ID);
+
     // Register table
     UniqueEntity.register(TABLE_ID);
 
diff --git a/packages/world-modules/src/modules/uniqueentity/constants.sol b/packages/world-modules/src/modules/uniqueentity/constants.sol
index 07c4691423..ebefa29b7b 100644
--- a/packages/world-modules/src/modules/uniqueentity/constants.sol
+++ b/packages/world-modules/src/modules/uniqueentity/constants.sol
@@ -2,12 +2,13 @@
 pragma solidity >=0.8.21;
 
 import { ResourceId } from "@latticexyz/world/src/WorldResourceId.sol";
-import { RESOURCE_TABLE, RESOURCE_SYSTEM } from "@latticexyz/world/src/worldResourceTypes.sol";
+import { RESOURCE_TABLE, RESOURCE_SYSTEM, RESOURCE_NAMESPACE } from "@latticexyz/world/src/worldResourceTypes.sol";
 
 bytes14 constant NAMESPACE = bytes14("uniqueEntity");
 bytes16 constant MODULE_NAME = bytes16("uniqueEntity");
 bytes16 constant SYSTEM_NAME = bytes16("system");
 bytes16 constant TABLE_NAME = bytes16("table");
 
+ResourceId constant NAMESPACE_ID = ResourceId.wrap(bytes32(abi.encodePacked(RESOURCE_NAMESPACE, NAMESPACE)));
 ResourceId constant TABLE_ID = ResourceId.wrap(bytes32(abi.encodePacked(RESOURCE_TABLE, NAMESPACE, TABLE_NAME)));
 ResourceId constant SYSTEM_ID = ResourceId.wrap((bytes32(abi.encodePacked(RESOURCE_SYSTEM, NAMESPACE, SYSTEM_NAME))));
diff --git a/packages/world-modules/test/PuppetModule.t.sol b/packages/world-modules/test/PuppetModule.t.sol
index 7e29308620..5025d49866 100644
--- a/packages/world-modules/test/PuppetModule.t.sol
+++ b/packages/world-modules/test/PuppetModule.t.sol
@@ -49,9 +49,25 @@ contract PuppetModuleTest is Test, GasReporter {
   function setUp() public {
     world = IBaseWorld(address(new World()));
     world.initialize(new CoreModule());
+  }
+
+  function _setupPuppet() internal {
     world.installModule(new PuppetModule(), new bytes(0));
 
+    // Register a new namespace and system
+    world.registerNamespace(systemId.getNamespaceId());
+    PuppetTestSystem system = new PuppetTestSystem();
+    world.registerSystem(systemId, system, true);
+
+    // Connect the puppet
+    puppet = PuppetTestSystem(createPuppet(world, systemId));
+  }
+
+  function _setupRootPuppet() internal {
+    world.installRootModule(new PuppetModule(), new bytes(0));
+
     // Register a new system
+    world.registerNamespace(systemId.getNamespaceId());
     PuppetTestSystem system = new PuppetTestSystem();
     world.registerSystem(systemId, system, true);
 
@@ -60,6 +76,8 @@ contract PuppetModuleTest is Test, GasReporter {
   }
 
   function testEmitOnPuppet() public {
+    _setupPuppet();
+
     vm.expectEmit(true, true, true, true);
     emit Hello("hello world");
     string memory result = puppet.echoAndEmit("hello world");
@@ -67,6 +85,23 @@ contract PuppetModuleTest is Test, GasReporter {
   }
 
   function testMsgSender() public {
+    _setupPuppet();
+
+    assertEq(puppet.msgSender(), address(this));
+  }
+
+  function testEmitOnRootPuppet() public {
+    _setupRootPuppet();
+
+    vm.expectEmit(true, true, true, true);
+    emit Hello("hello world");
+    string memory result = puppet.echoAndEmit("hello world");
+    assertEq(result, "hello world");
+  }
+
+  function testMsgSenderRootPuppet() public {
+    _setupRootPuppet();
+
     assertEq(puppet.msgSender(), address(this));
   }
 }
diff --git a/packages/world-modules/test/StandardDelegationsModule.t.sol b/packages/world-modules/test/StandardDelegationsModule.t.sol
index fd7b4a65de..adfc7d613e 100644
--- a/packages/world-modules/test/StandardDelegationsModule.t.sol
+++ b/packages/world-modules/test/StandardDelegationsModule.t.sol
@@ -25,6 +25,7 @@ import { CALLBOUND_DELEGATION, SYSTEMBOUND_DELEGATION, TIMEBOUND_DELEGATION } fr
 import { WorldTestSystem, WorldTestSystemReturn } from "@latticexyz/world/test/World.t.sol";
 
 contract StandardDelegationsModuleTest is Test, GasReporter {
+  using WorldResourceIdInstance for ResourceId;
   IBaseWorld private world;
   ResourceId private systemId =
     WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: "namespace", name: "testSystem" });
@@ -38,6 +39,7 @@ contract StandardDelegationsModuleTest is Test, GasReporter {
 
     // Register a new system
     WorldTestSystem system = new WorldTestSystem();
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
   }
 
diff --git a/packages/world-modules/test/SystemSwitch.t.sol b/packages/world-modules/test/SystemSwitch.t.sol
index cce9879230..6f8cf04f76 100644
--- a/packages/world-modules/test/SystemSwitch.t.sol
+++ b/packages/world-modules/test/SystemSwitch.t.sol
@@ -8,7 +8,7 @@ import { System } from "@latticexyz/world/src/System.sol";
 import { IBaseWorld } from "@latticexyz/world/src/codegen/interfaces/IBaseWorld.sol";
 import { World } from "@latticexyz/world/src/World.sol";
 import { CoreModule } from "@latticexyz/world/src/modules/core/CoreModule.sol";
-import { ResourceId, WorldResourceIdLib } from "@latticexyz/world/src/WorldResourceId.sol";
+import { ResourceId, WorldResourceIdLib, WorldResourceIdInstance } from "@latticexyz/world/src/WorldResourceId.sol";
 import { RESOURCE_SYSTEM } from "@latticexyz/world/src/worldResourceTypes.sol";
 import { ROOT_NAMESPACE } from "@latticexyz/world/src/constants.sol";
 import { SystemSwitch } from "../src/utils/SystemSwitch.sol";
@@ -38,6 +38,8 @@ contract EchoSystem is System {
 address constant caller = address(4232);
 
 contract SystemSwitchTest is Test, GasReporter {
+  using WorldResourceIdInstance for ResourceId;
+
   IBaseWorld world;
 
   EchoSystem systemA;
@@ -68,6 +70,10 @@ contract SystemSwitchTest is Test, GasReporter {
     rootSystemAId = WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: ROOT_NAMESPACE, name: "systemA" });
     rootSystemBId = WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: ROOT_NAMESPACE, name: "systemB" });
 
+    // Register namespaces
+    world.registerNamespace(systemAId.getNamespaceId());
+    world.registerNamespace(systemBId.getNamespaceId());
+
     // Register systems
     world.registerSystem(systemAId, systemA, true);
     world.registerSystem(systemBId, systemB, true);
diff --git a/packages/world-modules/test/UniqueEntityModule.t.sol b/packages/world-modules/test/UniqueEntityModule.t.sol
index 5979a67435..9808e28743 100644
--- a/packages/world-modules/test/UniqueEntityModule.t.sol
+++ b/packages/world-modules/test/UniqueEntityModule.t.sol
@@ -126,6 +126,7 @@ contract UniqueEntityModuleTest is Test, GasReporter {
       namespace: "somens",
       name: "echoUniqueEntity"
     });
+    world.registerNamespace(uniqueEntityTestSystemId.getNamespaceId());
     world.registerSystem(uniqueEntityTestSystemId, uniqueEntityTestSystem, true);
 
     // Execute `getUniqueEntity` from the context of a World
diff --git a/packages/world/gas-report.json b/packages/world/gas-report.json
index 09c68697d8..d1cb3e329a 100644
--- a/packages/world/gas-report.json
+++ b/packages/world/gas-report.json
@@ -69,7 +69,7 @@
     "file": "test/World.t.sol",
     "test": "testCallFromUnlimitedDelegation",
     "name": "register an unlimited delegation",
-    "gasUsed": 47638
+    "gasUsed": 47632
   },
   {
     "file": "test/World.t.sol",
@@ -93,7 +93,7 @@
     "file": "test/World.t.sol",
     "test": "testRegisterFunctionSelector",
     "name": "Register a function selector",
-    "gasUsed": 83149
+    "gasUsed": 83138
   },
   {
     "file": "test/World.t.sol",
@@ -105,19 +105,19 @@
     "file": "test/World.t.sol",
     "test": "testRegisterRootFunctionSelector",
     "name": "Register a root function selector",
-    "gasUsed": 80433
+    "gasUsed": 80444
   },
   {
     "file": "test/World.t.sol",
     "test": "testRegisterSystem",
     "name": "register a system",
-    "gasUsed": 164283
+    "gasUsed": 164317
   },
   {
     "file": "test/World.t.sol",
     "test": "testRegisterTable",
     "name": "Register a new table in the namespace",
-    "gasUsed": 636507
+    "gasUsed": 528361
   },
   {
     "file": "test/World.t.sol",
diff --git a/packages/world/src/AccessControl.sol b/packages/world/src/AccessControl.sol
index 988fd1b7f1..0933bec75c 100644
--- a/packages/world/src/AccessControl.sol
+++ b/packages/world/src/AccessControl.sol
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: MIT
 pragma solidity >=0.8.21;
 
+import { ResourceIds } from "@latticexyz/store/src/codegen/tables/ResourceIds.sol";
+
 import { ResourceId, WorldResourceIdInstance } from "./WorldResourceId.sol";
 import { IWorldErrors } from "./IWorldErrors.sol";
 
@@ -50,4 +52,15 @@ library AccessControl {
       revert IWorldErrors.World_AccessDenied(resourceId.toString(), caller);
     }
   }
+
+  /**
+   * @notice Check for existence of the given resource ID.
+   * @dev Reverts with IWorldErrors.World_ResourceNotFound if the resource does not exist.
+   * @param resourceId The resource ID to check existence for.
+   */
+  function requireExistence(ResourceId resourceId) internal view {
+    if (!ResourceIds._getExists(resourceId)) {
+      revert IWorldErrors.World_ResourceNotFound(resourceId, resourceId.toString());
+    }
+  }
 }
diff --git a/packages/world/src/modules/core/implementations/StoreRegistrationSystem.sol b/packages/world/src/modules/core/implementations/StoreRegistrationSystem.sol
index 1df3ca8a96..c380ce0cdd 100644
--- a/packages/world/src/modules/core/implementations/StoreRegistrationSystem.sol
+++ b/packages/world/src/modules/core/implementations/StoreRegistrationSystem.sol
@@ -5,7 +5,6 @@ import { IStoreHook, STORE_HOOK_INTERFACE_ID } from "@latticexyz/store/src/IStor
 import { StoreCore } from "@latticexyz/store/src/StoreCore.sol";
 import { FieldLayout } from "@latticexyz/store/src/FieldLayout.sol";
 import { Schema } from "@latticexyz/store/src/Schema.sol";
-import { ResourceIds } from "@latticexyz/store/src/codegen/tables/ResourceIds.sol";
 
 import { System } from "../../../System.sol";
 import { ResourceId, WorldResourceIdInstance } from "../../../WorldResourceId.sol";
@@ -14,8 +13,6 @@ import { AccessControl } from "../../../AccessControl.sol";
 import { requireInterface } from "../../../requireInterface.sol";
 import { revertWithBytes } from "../../../revertWithBytes.sol";
 
-import { Systems } from "../../../codegen/tables/Systems.sol";
-
 import { IWorldErrors } from "../../../IWorldErrors.sol";
 
 import { CORE_SYSTEM_ID } from "../constants.sol";
@@ -49,23 +46,16 @@ contract StoreRegistrationSystem is System, IWorldErrors {
     string[] calldata fieldNames
   ) public virtual {
     // Require the name to not be the namespace's root name
-    if (tableId.getName() == ROOT_NAME) revert World_InvalidResourceId(tableId, tableId.toString());
-
-    // If the namespace doesn't exist yet, register it
-    ResourceId namespaceId = tableId.getNamespaceId();
-    if (!ResourceIds._getExists(namespaceId)) {
-      // Since this is a root system, we're in the context of the World contract already,
-      // so we can use delegatecall to register the namespace
-      address coreSystemAddress = Systems._getSystem(CORE_SYSTEM_ID);
-      (bool success, bytes memory data) = coreSystemAddress.delegatecall(
-        abi.encodeCall(WorldRegistrationSystem.registerNamespace, (namespaceId))
-      );
-      if (!success) revertWithBytes(data);
-    } else {
-      // otherwise require caller to own the namespace
-      AccessControl.requireOwner(namespaceId, _msgSender());
+    if (tableId.getName() == ROOT_NAME) {
+      revert World_InvalidResourceId(tableId, tableId.toString());
     }
 
+    // Require the table's namespace to exist
+    AccessControl.requireExistence(tableId.getNamespaceId());
+
+    // Require the caller to own the table's namespace
+    AccessControl.requireOwner(tableId, _msgSender());
+
     // Register the table
     StoreCore.registerTable(tableId, fieldLayout, keySchema, valueSchema, keyNames, fieldNames);
   }
diff --git a/packages/world/src/modules/core/implementations/WorldRegistrationSystem.sol b/packages/world/src/modules/core/implementations/WorldRegistrationSystem.sol
index 21025a33c5..11cd866970 100644
--- a/packages/world/src/modules/core/implementations/WorldRegistrationSystem.sol
+++ b/packages/world/src/modules/core/implementations/WorldRegistrationSystem.sol
@@ -113,6 +113,13 @@ contract WorldRegistrationSystem is System, IWorldErrors {
       revert World_InvalidResourceType(RESOURCE_SYSTEM, systemId, systemId.toString());
     }
 
+    // Require the system's namespace to exist
+    ResourceId namespaceId = systemId.getNamespaceId();
+    AccessControl.requireExistence(namespaceId);
+
+    // Require the caller to own the namespace
+    AccessControl.requireOwner(namespaceId, _msgSender());
+
     // Require the provided address to implement the WorldContextConsumer interface
     requireInterface(address(system), WORLD_CONTEXT_CONSUMER_INTERFACE_ID);
 
@@ -127,15 +134,6 @@ contract WorldRegistrationSystem is System, IWorldErrors {
       revert World_SystemAlreadyExists(address(system));
     }
 
-    // If the namespace doesn't exist yet, register it
-    ResourceId namespaceId = systemId.getNamespaceId();
-    if (!ResourceIds._getExists(namespaceId)) {
-      registerNamespace(namespaceId);
-    } else {
-      // otherwise require caller to own the namespace
-      AccessControl.requireOwner(namespaceId, _msgSender());
-    }
-
     // Check if a system already exists at this system ID
     address existingSystem = Systems._getSystem(systemId);
 
diff --git a/packages/world/test/BatchCall.t.sol b/packages/world/test/BatchCall.t.sol
index 099f32ae59..e90b461f9f 100644
--- a/packages/world/test/BatchCall.t.sol
+++ b/packages/world/test/BatchCall.t.sol
@@ -8,7 +8,7 @@ import { StoreSwitch } from "@latticexyz/store/src/StoreSwitch.sol";
 import { World } from "../src/World.sol";
 import { System } from "../src/System.sol";
 import { UNLIMITED_DELEGATION } from "../src/constants.sol";
-import { ResourceId, WorldResourceIdLib } from "../src/WorldResourceId.sol";
+import { ResourceId, WorldResourceIdLib, WorldResourceIdInstance } from "../src/WorldResourceId.sol";
 import { RESOURCE_SYSTEM } from "../src/worldResourceTypes.sol";
 
 import { IWorldErrors } from "../src/IWorldErrors.sol";
@@ -47,6 +47,8 @@ contract TestSystem is System {
 }
 
 contract BatchCallTest is Test, GasReporter {
+  using WorldResourceIdInstance for ResourceId;
+
   IBaseWorld world;
   bytes14 namespace = "namespace";
   bytes16 name = "testSystem";
@@ -56,6 +58,7 @@ contract BatchCallTest is Test, GasReporter {
   function setUp() public {
     world = IBaseWorld(address(new World()));
     world.initialize(new CoreModule());
+    world.registerNamespace(systemId.getNamespaceId());
   }
 
   function testBatchCall() public {
diff --git a/packages/world/test/Utils.t.sol b/packages/world/test/Utils.t.sol
index b0458c9613..b2660f5210 100644
--- a/packages/world/test/Utils.t.sol
+++ b/packages/world/test/Utils.t.sol
@@ -9,6 +9,8 @@ import { World } from "../src/World.sol";
 import { IBaseWorld } from "../src/codegen/interfaces/IBaseWorld.sol";
 import { ResourceId, WorldResourceIdLib, WorldResourceIdInstance } from "../src/WorldResourceId.sol";
 import { RESOURCE_SYSTEM } from "../src/worldResourceTypes.sol";
+import { ResourceIds } from "@latticexyz/store/src/codegen/tables/ResourceIds.sol";
+import { StoreSwitch } from "@latticexyz/store/src/StoreSwitch.sol";
 
 import { CoreModule } from "../src/modules/core/CoreModule.sol";
 
@@ -27,12 +29,17 @@ contract UtilsTest is Test {
   function setUp() public {
     world = IBaseWorld(address(new World()));
     world.initialize(new CoreModule());
+    StoreSwitch.setStoreAddress(address(world));
   }
 
   function _registerAndGetNamespace(bytes14 namespace) internal returns (bytes16 returnedNamespace) {
     UtilsTestSystem testSystem = new UtilsTestSystem();
     bytes16 name = "testSystem";
     ResourceId systemId = WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: namespace, name: name });
+    ResourceId namespaceId = WorldResourceIdLib.encodeNamespace(namespace);
+    if (!ResourceIds.getExists(namespaceId)) {
+      world.registerNamespace(namespaceId);
+    }
     world.registerSystem(systemId, testSystem, true);
 
     bytes memory data = world.call(systemId, abi.encodeCall(UtilsTestSystem.systemNamespace, ()));
diff --git a/packages/world/test/World.t.sol b/packages/world/test/World.t.sol
index 678e276c8b..c6651b360e 100644
--- a/packages/world/test/World.t.sol
+++ b/packages/world/test/World.t.sol
@@ -308,6 +308,7 @@ contract WorldTest is Test, GasReporter {
       name: "testSystem"
     });
 
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, false);
     bytes memory result = world.call(systemId, abi.encodeCall(WorldTestSystem.getStoreAddress, ()));
 
@@ -431,6 +432,7 @@ contract WorldTest is Test, GasReporter {
     fieldNames[0] = "value1";
     fieldNames[1] = "value2";
     fieldNames[2] = "value3";
+    world.registerNamespace(tableId.getNamespaceId());
 
     startGasReport("Register a new table in the namespace");
     world.registerTable(tableId, fieldLayout, defaultKeySchema, valueSchema, keyNames, fieldNames);
@@ -460,7 +462,7 @@ contract WorldTest is Test, GasReporter {
       namespace: namespace,
       name: "otherTable"
     });
-    _expectAccessDenied(address(0x01), namespace, "", RESOURCE_NAMESPACE);
+    _expectAccessDenied(address(0x01), namespace, "otherTable", RESOURCE_TABLE);
     world.registerTable(otherTableId, fieldLayout, defaultKeySchema, valueSchema, keyNames, fieldNames);
 
     // Expect the World to not be allowed to call registerTable via an external call
@@ -505,15 +507,22 @@ contract WorldTest is Test, GasReporter {
     // Expect the system to have access to its own namespace
     assertTrue(ResourceAccess.get({ resourceId: namespaceId, caller: address(system) }));
 
-    ResourceId newNamespaceId = WorldResourceIdLib.encodeNamespace("newNamespace");
-    // Expect the namespace to be created if it doesn't exist yet
-    assertEq(NamespaceOwner.get(newNamespaceId), address(0));
-    world.registerSystem(
-      WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: "newNamespace", name: "testSystem" }),
-      new System(),
-      false
+    // Expect the registration to fail if the namespace does not exist yet
+    System newSystem = new System();
+    ResourceId invalidNamespaceSystemId = WorldResourceIdLib.encode({
+      typeId: RESOURCE_SYSTEM,
+      namespace: "newNamespace",
+      name: "testSystem"
+    });
+    assertEq(NamespaceOwner.get(invalidNamespaceSystemId.getNamespaceId()), address(0));
+    vm.expectRevert(
+      abi.encodeWithSelector(
+        IWorldErrors.World_ResourceNotFound.selector,
+        invalidNamespaceSystemId.getNamespaceId(),
+        invalidNamespaceSystemId.getNamespaceId().toString()
+      )
     );
-    assertEq(NamespaceOwner.get(newNamespaceId), address(this));
+    world.registerSystem(invalidNamespaceSystemId, newSystem, false);
 
     // Expect an error when registering an existing system at a new system ID
     vm.expectRevert(abi.encodeWithSelector(IWorldErrors.World_SystemAlreadyExists.selector, address(system)));
@@ -527,7 +536,6 @@ contract WorldTest is Test, GasReporter {
     world.registerSystem(systemId, system, true);
 
     // Expect an error when registering a system at an existing resource ID of a different type
-    System newSystem = new System();
     ResourceId tableId = WorldResourceIdLib.encode({ typeId: RESOURCE_TABLE, namespace: "", name: "testTable" });
     world.registerTable(
       tableId,
@@ -576,7 +584,7 @@ contract WorldTest is Test, GasReporter {
       )
     );
     world.registerSystem(
-      WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: "someNamespace", name: "invalidSystem" }),
+      WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: "", name: "invalidSystem" }),
       System(address(world)),
       true
     );
@@ -591,6 +599,7 @@ contract WorldTest is Test, GasReporter {
       namespace: namespace,
       name: systemName
     });
+    world.registerNamespace(systemId.getNamespaceId());
 
     // Register a system
     System oldSystem = new System();
@@ -631,6 +640,10 @@ contract WorldTest is Test, GasReporter {
   }
 
   function testInvalidIds() public {
+    // Register the namespaces
+    world.registerNamespace(WorldResourceIdLib.encodeNamespace("namespace"));
+    world.registerNamespace(WorldResourceIdLib.encodeNamespace("namespace2"));
+
     // Register a new table
     ResourceId tableId = WorldResourceIdLib.encode({ typeId: RESOURCE_TABLE, namespace: "namespace", name: "name" });
     world.registerTable(
@@ -706,6 +719,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "testSetRecord",
       name: "testTable"
     });
+    world.registerNamespace(tableId.getNamespaceId());
     // Register a new table
     world.registerTable(
       tableId,
@@ -741,6 +755,7 @@ contract WorldTest is Test, GasReporter {
     ResourceId tableId = WorldResourceIdLib.encode({ typeId: RESOURCE_TABLE, namespace: namespace, name: name });
     FieldLayout fieldLayout = Bool.getFieldLayout();
     Schema valueSchema = Bool.getValueSchema();
+    world.registerNamespace(tableId.getNamespaceId());
 
     // Register a new table
     world.registerTable(tableId, fieldLayout, defaultKeySchema, valueSchema, new string[](1), new string[](1));
@@ -772,6 +787,7 @@ contract WorldTest is Test, GasReporter {
     Schema valueSchema = AddressArray.getValueSchema();
 
     // Register a new table
+    world.registerNamespace(tableId.getNamespaceId());
     world.registerTable(tableId, fieldLayout, defaultKeySchema, valueSchema, new string[](1), new string[](1));
 
     // Create data
@@ -817,6 +833,7 @@ contract WorldTest is Test, GasReporter {
     Schema valueSchema = Bool.getValueSchema();
 
     // Register a new table
+    world.registerNamespace(tableId.getNamespaceId());
     world.registerTable(tableId, fieldLayout, defaultKeySchema, valueSchema, new string[](1), new string[](1));
 
     // Write data to the table and expect it to be written
@@ -855,6 +872,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "namespace",
       name: "testSystem"
     });
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, false);
 
     // Call a system function without arguments via the World
@@ -933,6 +951,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "namespace",
       name: "testSystem"
     });
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     address caller = address(1);
@@ -954,6 +973,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "namespace",
       name: "testSystem"
     });
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     // Register an unlimited delegation
@@ -983,6 +1003,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "namespace",
       name: "testSystem"
     });
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     // Expect a revert when attempting to perform a call on behalf of an address that doesn't have a delegation
@@ -1005,6 +1026,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "namespace",
       name: "testSystem"
     });
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     // Register a limited delegation
@@ -1022,6 +1044,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "namespace",
       name: "testSystem"
     });
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     // Register a delegation control mock system
@@ -1031,6 +1054,7 @@ contract WorldTest is Test, GasReporter {
       namespace: "delegation",
       name: "mock"
     });
+    world.registerNamespace(delegationControlMockId.getNamespaceId());
     world.registerSystem(delegationControlMockId, delegationControlMock, true);
 
     address delegator = address(1);
@@ -1224,6 +1248,7 @@ contract WorldTest is Test, GasReporter {
 
     // Register a new system
     WorldTestSystem system = new WorldTestSystem();
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     // Expect the registration to fail if the contract does not implement the system hook interface
@@ -1268,6 +1293,7 @@ contract WorldTest is Test, GasReporter {
     });
 
     // Register a new system
+    world.registerNamespace(systemId.getNamespaceId());
     WorldTestSystem system = new WorldTestSystem();
     world.registerSystem(systemId, system, false);
 
@@ -1309,6 +1335,7 @@ contract WorldTest is Test, GasReporter {
       name: "testTable"
     });
     // Register a new table
+    world.registerNamespace(tableId.getNamespaceId());
     world.registerTable(
       tableId,
       Bool.getFieldLayout(),
@@ -1337,6 +1364,7 @@ contract WorldTest is Test, GasReporter {
       name: "testTable"
     });
     // Register a new table
+    world.registerNamespace(tableId.getNamespaceId());
     world.registerTable(
       tableId,
       Bool.getFieldLayout(),
@@ -1382,6 +1410,7 @@ contract WorldTest is Test, GasReporter {
     });
     // Register a new non-root system
     WorldTestSystem system = new WorldTestSystem();
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, false);
 
     // Call the sysyem
@@ -1397,6 +1426,7 @@ contract WorldTest is Test, GasReporter {
 
     // Register a new system
     WorldTestSystem system = new WorldTestSystem();
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     startGasReport("Register a function selector");
@@ -1428,6 +1458,7 @@ contract WorldTest is Test, GasReporter {
 
     // Register a new system
     WorldTestSystem system = new WorldTestSystem();
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
 
     string memory worldFunc = "testSelector()";
@@ -1495,6 +1526,7 @@ contract WorldTest is Test, GasReporter {
     bytes16 name = "testSystem";
     ResourceId systemId = WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: namespace, name: name });
 
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
     world.registerRootFunctionSelector(systemId, "receiveEther()", WorldTestSystem.receiveEther.selector);
 
@@ -1521,6 +1553,7 @@ contract WorldTest is Test, GasReporter {
     bytes14 namespace = "noroot";
     bytes16 name = "testSystem";
     ResourceId systemId = WorldResourceIdLib.encode({ typeId: RESOURCE_SYSTEM, namespace: namespace, name: name });
+    world.registerNamespace(systemId.getNamespaceId());
     world.registerSystem(systemId, system, true);
     world.registerRootFunctionSelector(systemId, "msgSender()", WorldTestSystem.msgSender.selector);
 
diff --git a/packages/world/test/WorldBalance.t.sol b/packages/world/test/WorldBalance.t.sol
index c43c09b0dc..10c44dfd45 100644
--- a/packages/world/test/WorldBalance.t.sol
+++ b/packages/world/test/WorldBalance.t.sol
@@ -39,6 +39,8 @@ contract WorldBalanceTest is Test, GasReporter {
     world.initialize(new CoreModule());
     StoreSwitch.setStoreAddress(address(world));
 
+    world.registerNamespace(namespaceId);
+
     world.registerSystem(rootSystemId, rootSystem, true);
     world.registerSystem(nonRootSystemId, nonRootSystem, true);
 
diff --git a/packages/world/test/WorldDynamicUpdate.t.sol b/packages/world/test/WorldDynamicUpdate.t.sol
index f8680e6fa0..a70d6e7b5e 100644
--- a/packages/world/test/WorldDynamicUpdate.t.sol
+++ b/packages/world/test/WorldDynamicUpdate.t.sol
@@ -64,6 +64,7 @@ contract UpdateInDynamicFieldTest is Test, GasReporter {
     tableId = WorldResourceIdLib.encode({ typeId: RESOURCE_TABLE, namespace: namespace, name: name });
 
     // Register a new table
+    world.registerNamespace(tableId.getNamespaceId());
     world.registerTable(tableId, fieldLayout, defaultKeySchema, valueSchema, new string[](1), new string[](1));
 
     // Create data