diff --git a/packages/pds/src/api/com/atproto/repo/createRecord.ts b/packages/pds/src/api/com/atproto/repo/createRecord.ts
index 978a3945253..0f28f8cbb4f 100644
--- a/packages/pds/src/api/com/atproto/repo/createRecord.ts
+++ b/packages/pds/src/api/com/atproto/repo/createRecord.ts
@@ -33,6 +33,11 @@ export default function (server: Server, ctx: AppContext) {
           'Unvalidated writes are not yet supported.',
         )
       }
+      if (collection === ids.AppBskyFeedPost && rkey) {
+        throw new InvalidRequestError(
+          'Custom rkeys for post records are not currently supported.',
+        )
+      }
 
       const swapCommitCid = swapCommit ? CID.parse(swapCommit) : undefined