--- a/toolkit/themes/osx/global/button.css
+++ b/toolkit/themes/osx/global/button.css
@@ -9,23 +9,23 @@ button {
   /* The horizontal margin used here come from the Aqua Human Interface
      Guidelines, there should be 12 pixels between two buttons. */
   margin: 5px 6px 3px;
   min-width: 79px;
   color: ButtonText;
   text-shadow: none;
 }
 
-button:hover:active {
+button:not([disabled="true"]):hover:active {
   color: -moz-mac-buttonactivetext;
 }
 
 /* When the window isn't focused, the default button background isn't drawn,
  * so don't change the text color then: */
-button[default="true"]:not(:-moz-window-inactive) {
+button[default="true"]:not([disabled="true"]):not(:-moz-window-inactive) {
   color: -moz-mac-defaultbuttontext;
 }
 
 /* Likewise, when active (mousedown) but not hovering, the default button
  * background isn't drawn, override the previous selector for that case: */
 button[default="true"]:not(:hover):active {
   color: ButtonText;
 }