diff --git a/e2e/packages/contracts/mud.config.ts b/e2e/packages/contracts/mud.config.ts
index 318ed576670..762ce21584e 100644
--- a/e2e/packages/contracts/mud.config.ts
+++ b/e2e/packages/contracts/mud.config.ts
@@ -25,5 +25,17 @@ export default mudConfig({
         value: "uint32[]",
       },
     },
+    Multi: {
+      keySchema: {
+        a: "uint32",
+        b: "bool",
+        c: "uint256",
+        d: "int120",
+      },
+      schema: {
+        num: "int256",
+        value: "bool",
+      },
+    },
   },
 });
diff --git a/e2e/packages/sync-test/data/callWorld.ts b/e2e/packages/sync-test/data/callWorld.ts
index d7d94551653..ec8bfa8c594 100644
--- a/e2e/packages/sync-test/data/callWorld.ts
+++ b/e2e/packages/sync-test/data/callWorld.ts
@@ -8,7 +8,11 @@ type Args<Method extends keyof IWorld> = IWorld[Method] extends (...args: any) =
 export function callWorld<Method extends keyof IWorld>(page: Page, method: Method, args: Args<Method>) {
   return page.evaluate(
     ([_method, _args]) => {
-      return window["worldSend"](_method, _args).then((tx) => tx.wait());
+      return window["worldSend"](_method, _args)
+        .then((tx) => tx.wait())
+        .catch((e) => {
+          throw new Error([`Error executing ${_method} with args:`, JSON.stringify(_args), e].join("\n\n"));
+        });
     },
     [method, args]
   );
diff --git a/e2e/packages/sync-test/data/encodeTestData.test.ts b/e2e/packages/sync-test/data/encodeTestData.test.ts
index 59a5631fa6d..90507dc4660 100644
--- a/e2e/packages/sync-test/data/encodeTestData.test.ts
+++ b/e2e/packages/sync-test/data/encodeTestData.test.ts
@@ -2,7 +2,7 @@ import { describe, expect, it } from "vitest";
 import { encodeTestData } from "./encodeTestData";
 
 describe("encodeTestData", () => {
-  it("should encode test data", () => {
+  it("should encode numbers", () => {
     expect(encodeTestData({ Number: [{ key: { key: 42 }, value: { value: 1337 } }] })).toStrictEqual({
       Number: [{ key: ["0x000000000000000000000000000000000000000000000000000000000000002a"], value: "0x00000539" }],
     });
diff --git a/e2e/packages/sync-test/data/encodeTestData.ts b/e2e/packages/sync-test/data/encodeTestData.ts
index 2661c706811..f4ba27153b3 100644
--- a/e2e/packages/sync-test/data/encodeTestData.ts
+++ b/e2e/packages/sync-test/data/encodeTestData.ts
@@ -1,6 +1,6 @@
 import { mapObject } from "@latticexyz/utils";
 import { Data, EncodedData } from "./types";
-import { encodeAbiParameters, toHex, encodePacked } from "viem";
+import { encodeAbiParameters, toHex, encodePacked, numberToHex } from "viem";
 import config from "../../contracts/mud.config";
 
 /**
@@ -10,9 +10,13 @@ export function encodeTestData(testData: Data) {
   return mapObject(testData, (records, table) =>
     records
       ? records.map((record) => ({
-          key: Object.values(record.key).map((key) =>
-            encodeAbiParameters([{ type: "bytes32" }], [toHex(key as any, { size: 32 })])
-          ),
+          key: Object.entries(record.key).map(([keyName, keyValue]) => {
+            const signed = config.tables[table].keySchema[keyName]?.startsWith("int");
+            return encodeAbiParameters(
+              [{ type: "bytes32" }],
+              [signed ? numberToHex(keyValue as any, { size: 32, signed }) : toHex(keyValue as any, { size: 32 })]
+            );
+          }),
           value: encodePacked(Object.values(config.tables[table].schema), Object.values(record.value)),
         }))
       : undefined
diff --git a/e2e/packages/sync-test/data/mergeTestData.ts b/e2e/packages/sync-test/data/mergeTestData.ts
index e03aa54e084..1ef76b2e753 100644
--- a/e2e/packages/sync-test/data/mergeTestData.ts
+++ b/e2e/packages/sync-test/data/mergeTestData.ts
@@ -1,5 +1,6 @@
 import { mapObject } from "@latticexyz/utils";
 import { Data, Datum } from "./types";
+import { serialize } from "./utils";
 
 /**
  * Merges an array of test data by merging and filtering the records for each table,
@@ -12,7 +13,7 @@ export function mergeTestData(...testDatas: Data[]) {
     for (const [table, records] of Object.entries(testData)) {
       recordsByTableByKeys[table] ??= {};
       for (const record of records) {
-        recordsByTableByKeys[table][JSON.stringify(record.key)] = record;
+        recordsByTableByKeys[table][serialize(record.key)] = record;
       }
     }
   }
diff --git a/e2e/packages/sync-test/data/readClientStore.ts b/e2e/packages/sync-test/data/readClientStore.ts
index 1fb293ab4e9..5e645191100 100644
--- a/e2e/packages/sync-test/data/readClientStore.ts
+++ b/e2e/packages/sync-test/data/readClientStore.ts
@@ -2,6 +2,7 @@ import { Page } from "@playwright/test";
 
 // Extract the storeCache type directly from the client
 import { setup } from "../../client-vanilla/src/mud/setup";
+import { deserialize, serialize } from "./utils";
 type StoreCache = Awaited<ReturnType<typeof setup>>["network"]["storeCache"];
 
 /**
@@ -9,8 +10,45 @@ type StoreCache = Awaited<ReturnType<typeof setup>>["network"]["storeCache"];
  * This is necessary because `page.evaluate` can only transmit serialisable data,
  * so we can't just return the entire client store (which includes functions to read data)
  */
-export async function readClientStore(page: Page, selector: Parameters<StoreCache["get"]>): Promise<StoreCache> {
-  return page.evaluate((_selector) => {
-    return window["storeCache"].get(..._selector);
+export async function readClientStore(
+  page: Page,
+  [namespace, table, key]: Parameters<StoreCache["get"]>
+): Promise<Record<string, unknown> | undefined> {
+  const selector = [namespace, table, serialize(key)];
+  const serializedValue = await page.evaluate((_selector) => {
+    const [_namespace, _table, _key] = _selector;
+    const result = window["storeCache"].get(_namespace, _table, deserialize(_key));
+    return result ? serialize(result) : undefined;
+
+    /**
+     * Helper to serialize values that are not natively serializable and therefore not transferrable to the page
+     * For now only `bigint` needs serialization.
+     */
+    function serialize(obj: unknown): string {
+      return JSON.stringify(obj, (_, v) => (typeof v === "bigint" ? `bigint(${v.toString()})` : v));
+    }
+
+    /**
+     * Helper to deserialize values that were serialized by `serialize` (because they are not natively serializable).
+     * For now only `bigint` is serialized and need to be deserialized here.
+     */
+    function deserialize(blob: string): Record<string, unknown> {
+      const obj = JSON.parse(blob);
+
+      // Check whether the value matches the mattern `${number}n`
+      // (serialization of bigint in `serialize`)
+      // and turn it back into a bigint
+      const regex = /^bigint\((.*)\)$/; // Regular expression pattern.
+      for (const [key, value] of Object.entries(obj)) {
+        const match = typeof value === "string" && value.match(regex); // Attempt to match the pattern.
+        if (match) {
+          obj[key] = BigInt(match[1]);
+        }
+      }
+
+      return obj;
+    }
   }, selector);
+
+  return serializedValue ? deserialize(serializedValue) : undefined;
 }
diff --git a/e2e/packages/sync-test/data/testData.ts b/e2e/packages/sync-test/data/testData.ts
index 0384d5f4970..9c24b99fe68 100644
--- a/e2e/packages/sync-test/data/testData.ts
+++ b/e2e/packages/sync-test/data/testData.ts
@@ -7,6 +7,12 @@ import { Data } from "./types";
 export const testData1 = {
   Number: [{ key: { key: 1 }, value: { value: 42 } }],
   Vector: [{ key: { key: 1 }, value: { x: 1, y: 2 } }],
+  Multi: [
+    {
+      key: { a: 9999, b: true, c: BigInt(42), d: BigInt(-999) },
+      value: { num: BigInt(1337), value: true },
+    },
+  ],
 } satisfies Data;
 
 export const testData2 = {
@@ -18,4 +24,14 @@ export const testData2 = {
     { key: { key: 1 }, value: { x: 1, y: 42 } },
     { key: { key: 32 }, value: { x: 1, y: -42 } },
   ],
+  Multi: [
+    {
+      key: { a: 9999, b: true, c: BigInt(42), d: BigInt(-999) },
+      value: { num: BigInt(31337), value: false },
+    },
+    {
+      key: { a: 9998, b: true, c: BigInt(42), d: BigInt(-999) },
+      value: { num: BigInt(0), value: true },
+    },
+  ],
 } satisfies Data;
diff --git a/e2e/packages/sync-test/data/utils.ts b/e2e/packages/sync-test/data/utils.ts
new file mode 100644
index 00000000000..878f94fdf38
--- /dev/null
+++ b/e2e/packages/sync-test/data/utils.ts
@@ -0,0 +1,28 @@
+/**
+ * Helper to serialize values that are not natively serializable and therefore not transferrable to the page
+ * For now only `bigint` needs serialization.
+ */
+export function serialize(obj: unknown): string {
+  return JSON.stringify(obj, (_, v) => (typeof v === "bigint" ? `bigint(${v.toString()})` : v));
+}
+
+/**
+ * Helper to deserialize values that were serialized by `serialize` (because they are not natively serializable).
+ * For now only `bigint` is serialized and need to be deserialized here.
+ */
+export function deserialize(blob: string): Record<string, unknown> {
+  const obj = JSON.parse(blob);
+
+  // Check whether the value matches the mattern `${number}n`
+  // (serialization of bigint in `serialize`)
+  // and turn it back into a bigint
+  const regex = /^bigint\((.*)\)$/; // Regular expression pattern.
+  for (const [key, value] of Object.entries(obj)) {
+    const match = typeof value === "string" && value.match(regex); // Attempt to match the pattern.
+    if (match) {
+      obj[key] = BigInt(match[1]);
+    }
+  }
+
+  return obj;
+}