diff --git a/toolkit/mozapps/extensions/LightweightThemeManager.jsm b/toolkit/mozapps/extensions/LightweightThemeManager.jsm
index 66761efe2b..5856bfa912 100644
--- a/toolkit/mozapps/extensions/LightweightThemeManager.jsm
+++ b/toolkit/mozapps/extensions/LightweightThemeManager.jsm
@@ -386,7 +386,13 @@ this.LightweightThemeManager = {
       return;
     }
 
-    aCallback([new AddonWrapper(a) for each (a in this.usedThemes)]);
+    // Tycho: aCallback([new AddonWrapper(a) for each (a in this.usedThemes)]);
+    let result = [];
+    for each(let a in this.usedThemes) {
+      result.push(new AddonWrapper(a));
+    }
+    
+    aCallback(result);
   },
 };