diff --git a/packages/actor-core/src/common/utils.ts b/packages/actor-core/src/common/utils.ts
index 65103947a..40bb69603 100644
--- a/packages/actor-core/src/common/utils.ts
+++ b/packages/actor-core/src/common/utils.ts
@@ -3,7 +3,12 @@ import type { ContentfulStatusCode } from "hono/utils/http-status";
 import * as errors from "@/actor/errors";
 import type { Logger } from "./log";
 
-export const ActorKeySchema = z.array(z.string());
+// Maximum size of a key component in bytes
+// Set to 128 bytes to allow for separators and escape characters in the full key
+// Cloudflare's maximum key size is 512 bytes, so we need to be significantly smaller
+export const MAX_KEY_SIZE = 128;
+
+export const ActorKeySchema = z.array(z.string().max(MAX_KEY_SIZE));
 
 export type ActorKey = z.infer<typeof ActorKeySchema>;