Index: branches/5.3.x/core/admin_templates/submissions/submission_view.tpl
===================================================================
diff -u -N -r15483 -r15902
--- branches/5.3.x/core/admin_templates/submissions/submission_view.tpl	(.../submission_view.tpl)	(revision 15483)
+++ branches/5.3.x/core/admin_templates/submissions/submission_view.tpl	(.../submission_view.tpl)	(revision 15902)
@@ -210,10 +210,10 @@
 				$merge_to_submission.disabled = !$do_merge;
 
 				if ($do_merge) {
-					$('#merge_submission').removeClass('button-disabled').addClass('button').attr('disabled', '');
+					$('#merge_submission').removeClass('button-disabled').addClass('button').prop('disabled', false);
 				}
 				else {
-					$('#merge_submission').removeClass('button').addClass('button-disabled').attr('disabled', 'disabled');
+					$('#merge_submission').removeClass('button').addClass('button-disabled').prop('disabled', true);
 				}
 			}
 		</script>