diff --git a/mozilla/themes/classic/global/unix/menulist.css b/mozilla/themes/classic/global/unix/menulist.css
index e7b836a6c41..46d05db73d1 100644
--- a/mozilla/themes/classic/global/unix/menulist.css
+++ b/mozilla/themes/classic/global/unix/menulist.css
@@ -106,7 +106,7 @@
     {
       padding             : 0px 1px 0px 1px;
       min-width           : 0px;  /* should be in content*/
-      max-width           : auto; /* should be in content*/
+      max-width           : none; /* should be in content*/
       border              : 1px solid window;
     }
 
diff --git a/mozilla/themes/classic/global/win/menulist.css b/mozilla/themes/classic/global/win/menulist.css
index e7b836a6c41..46d05db73d1 100644
--- a/mozilla/themes/classic/global/win/menulist.css
+++ b/mozilla/themes/classic/global/win/menulist.css
@@ -106,7 +106,7 @@
     {
       padding             : 0px 1px 0px 1px;
       min-width           : 0px;  /* should be in content*/
-      max-width           : auto; /* should be in content*/
+      max-width           : none; /* should be in content*/
       border              : 1px solid window;
     }
 
diff --git a/mozilla/themes/modern/global/menulist.css b/mozilla/themes/modern/global/menulist.css
index 1c92ed38dd2..f769b83e707 100644
--- a/mozilla/themes/modern/global/menulist.css
+++ b/mozilla/themes/modern/global/menulist.css
@@ -157,7 +157,7 @@
     {
       padding             : 0px;
       min-width: 0px;
-      max-width: auto;
+      max-width: none;
     }
 
   menulist > menupopup > menuitem > .menu-left