diff --git a/src/zen/workspaces/ZenWorkspaces.mjs b/src/zen/workspaces/ZenWorkspaces.mjs
index dc1f29623..2c44c0b29 100644
--- a/src/zen/workspaces/ZenWorkspaces.mjs
+++ b/src/zen/workspaces/ZenWorkspaces.mjs
@@ -23,6 +23,8 @@ class nsZenWorkspaces {
     direction: null,
   };
 
+  _workspaceCache = {};
+
   #lastScrollTime = 0;
 
   bookmarkMenus = [