Index: wp-admin/js/custom-background.js
===================================================================
--- wp-admin/js/custom-background.js	(revision 21902)
+++ wp-admin/js/custom-background.js	(working copy)
@@ -61,6 +61,13 @@
 					$(this).fadeOut(2);
 			});
 		});
+
+		toggleUploadButton = function() {
+			$('#upload-form #submit').prop( 'disabled', '' === $('#upload').val() );
+		};
+	
+		toggleUploadButton();
+		$('#upload').change( toggleUploadButton );
 	});
 
-})(jQuery);
\ No newline at end of file
+})(jQuery);
Index: wp-admin/js/custom-header.js
===================================================================
--- wp-admin/js/custom-header.js	(revision 0)
+++ wp-admin/js/custom-header.js	(working copy)
@@ -0,0 +1,12 @@
+(function($) {
+
+	$(document).ready( function() {
+		toggleUploadButton = function() {
+			$('#upload-form #submit').prop( 'disabled', '' === $('#upload').val() );
+		};
+	
+		toggleUploadButton();
+		$('#upload').change( toggleUploadButton );
+	});
+
+})(jQuery);
Index: wp-includes/script-loader.php
===================================================================
--- wp-includes/script-loader.php	(revision 21902)
+++ wp-includes/script-loader.php	(working copy)
@@ -440,8 +440,9 @@
 			'saveAlert' => __('The changes you made will be lost if you navigate away from this page.')
 		) );
 
-		$scripts->add( 'custom-background', "/wp-admin/js/custom-background$suffix.js", array('farbtastic'), false, 1 );
-		$scripts->add( 'media-gallery', "/wp-admin/js/media-gallery$suffix.js", array('jquery'), false, 1 );
+		$scripts->add( 'custom-header', "/wp-admin/js/custom-header$suffix.js", array( 'jquery' ), false, 1 );
+		$scripts->add( 'custom-background', "/wp-admin/js/custom-background$suffix.js", array( 'farbtastic' ), false, 1 );
+		$scripts->add( 'media-gallery', "/wp-admin/js/media-gallery$suffix.js", array( 'jquery' ), false, 1 );
 	}
 }