diff --git a/browser/components/sessionstore/src/nsSessionStore.js b/browser/components/sessionstore/src/nsSessionStore.js
index c2da560722bf..07361f453097 100644
--- a/browser/components/sessionstore/src/nsSessionStore.js
+++ b/browser/components/sessionstore/src/nsSessionStore.js
@@ -2518,7 +2518,7 @@ SessionStoreService.prototype = {
       // at startup we don't accidentally add them to a popup window
       do {
         total.unshift(lastClosedWindowsCopy.shift())
-      } while (total[0].isPopup)
+      } while (total[0].isPopup && lastClosedWindowsCopy.length > 0)
     }
 #endif