diff --git a/packages/backend/src/misc/is-duplicate-key-value-error.ts b/packages/backend/src/misc/is-duplicate-key-value-error.ts
index 18d22bb77c..670277fe1a 100644
--- a/packages/backend/src/misc/is-duplicate-key-value-error.ts
+++ b/packages/backend/src/misc/is-duplicate-key-value-error.ts
@@ -1,3 +1,4 @@
 export function isDuplicateKeyValueError(e: unknown | Error): boolean {
-	return (e as Error).message?.startsWith("duplicate key value");
+	const nodeError = e as NodeJS.ErrnoException;
+	return nodeError.code === "23505";
 }