diff --git a/packages/cli/src/deploy/resolveConfig.ts b/packages/cli/src/deploy/resolveConfig.ts
index 034af8bf41..6c4d3d7039 100644
--- a/packages/cli/src/deploy/resolveConfig.ts
+++ b/packages/cli/src/deploy/resolveConfig.ts
@@ -79,6 +79,12 @@ export function resolveConfig<config extends ConfigInput>({
     };
   });
 
+  systems.forEach((item, index) => {
+    if (systems.some((elem, idx) => elem.systemId === item.systemId && idx !== index)) {
+      throw new Error(`Duplicate system ID ${item.systemId} found in the config.`);
+    }
+  });
+
   // resolve allowedSystemIds
   // TODO: resolve this at deploy time so we can allow for arbitrary system IDs registered in the world as the source-of-truth rather than config
   const systemsWithAccess = systems.map(({ allowedAddresses, allowedSystemIds, ...system }) => {