diff --git a/src/hooks/bundled/session-memory/handler.ts b/src/hooks/bundled/session-memory/handler.ts
index ed70e42c9a7..f85450a16c9 100644
--- a/src/hooks/bundled/session-memory/handler.ts
+++ b/src/hooks/bundled/session-memory/handler.ts
@@ -332,7 +332,7 @@ const saveSessionToMemory: HookHandler = async (event) => {
     // one silently overwrites the earlier memory entry.
     if (!slug) {
       const timeSlug = now.toISOString().split("T")[1].split(".")[0].replace(/:/g, "");
-      const rand = (Math.random().toString(36) + "0000").slice(2, 6); // guaranteed 4-char
+      const rand = Math.random().toString(36).slice(2, 6).padEnd(4, "0");
       slug = `${timeSlug.slice(0, 6)}-${rand}`;
       log.debug("Using fallback timestamp slug", { slug });
     }