diff --git a/mozilla/xpinstall/res/skin/xpinstall.css b/mozilla/xpinstall/res/skin/xpinstall.css
index ce8df0e56eb..c7db02791a3 100644
--- a/mozilla/xpinstall/res/skin/xpinstall.css
+++ b/mozilla/xpinstall/res/skin/xpinstall.css
@@ -65,6 +65,7 @@ div#interiorTitle {
 tree#modulesTree {
   background-color          : transparent ! important;
   height                    : 16ex;
+  width                     : 32em;
 }
 
 treecell#moduleName {