diff --git a/packages/backend-core/src/cache/tests/docWritethrough.spec.ts b/packages/backend-core/src/cache/tests/docWritethrough.spec.ts
index 5fe09b95ff..1ae85cfd0b 100644
--- a/packages/backend-core/src/cache/tests/docWritethrough.spec.ts
+++ b/packages/backend-core/src/cache/tests/docWritethrough.spec.ts
@@ -32,7 +32,7 @@ describe("docWritethrough", () => {
 
   describe("patch", () => {
     function generatePatchObject(fieldCount: number) {
-      const keys = generator.unique(() => generator.word(), fieldCount)
+      const keys = generator.unique(() => generator.guid(), fieldCount)
       return keys.reduce((acc, c) => {
         acc[c] = generator.word()
         return acc