--- a/browser/base/content/aboutDialog.js
+++ b/browser/base/content/aboutDialog.js
@@ -61,16 +61,22 @@ function init(aEvent) {
       relNotesLink.href = relNotesURL;
       relNotesLink.hidden = false;
     }
   }
 
   if (AppConstants.MOZ_UPDATER) {
     gAppUpdater = new appUpdater();
 
+    let button = gAppUpdater.updateDeck.selectedPanel.querySelector("button");
+    if (button && (!document.commandDispatcher.focusedElement || // don't steal the focus
+                   document.commandDispatcher.focusedElement.localName == "button")) { // except from the other buttons
+      button.focus();
+    }
+
     let channelLabel = document.getElementById("currentChannel");
     let currentChannelText = document.getElementById("currentChannelText");
     channelLabel.value = UpdateUtils.UpdateChannel;
     if (/^release($|\-)/.test(channelLabel.value))
         currentChannelText.hidden = true;
   }
 
   if (AppConstants.platform == "macosx") {