--- a/toolkit/themes/osx/global/media/videocontrols.css
+++ b/toolkit/themes/osx/global/media/videocontrols.css
@@ -385,17 +385,17 @@ html|table {
   .muteButton[muted] {
     background-image: url(chrome://global/skin/media/unmuteButton@2x.png);
     background-size: 33px 28px;
   }
   .muteButton[noAudio] {
     background-image: url(chrome://global/skin/media/noAudio@2x.png);
     background-size: 33px 28px;
   }
-  .closeCaptionButton {
+  .closedCaptionButton {
     background-image: url(chrome://global/skin/media/closeCaptionButton@2x.png);
     background-size: 28px 28px;
   }
   .fullscreenButton {
     background-image: -moz-image-rect(url("chrome://global/skin/media/fullscreenButton@2x.png"), 0, 32, 32, 0);
     background-size: 16px 16px;
   }
   .fullscreenButton[fullscreened] {