Index: src/wp-admin/includes/options.php
===================================================================
--- src/wp-admin/includes/options.php	(revision 40424)
+++ src/wp-admin/includes/options.php	(working copy)
@@ -53,7 +53,7 @@
 			if ( "date_format_custom_radio" != $(this).attr("id") )
 				$( "input[name='date_format_custom']" ).val( $( this ).val() ).siblings( '.example' ).text( $( this ).parent( 'label' ).children( '.format-i18n' ).text() );
 		});
-		$("input[name='date_format_custom']").focus(function(){
+		$( 'input[name="date_format_custom"]' ).on( 'click input', function() {
 			$( '#date_format_custom_radio' ).prop( 'checked', true );
 		});

@@ -61,7 +61,7 @@
 			if ( "time_format_custom_radio" != $(this).attr("id") )
 				$( "input[name='time_format_custom']" ).val( $( this ).val() ).siblings( '.example' ).text( $( this ).parent( 'label' ).children( '.format-i18n' ).text() );
 		});
-		$("input[name='time_format_custom']").focus(function(){
+		$( 'input[name="time_format_custom"]' ).on( 'click input', function() {
 			$( '#time_format_custom_radio' ).prop( 'checked', true );
 		});
 		$("input[name='date_format_custom'], input[name='time_format_custom']").change( function() {