diff --git a/wp-includes/default-widgets.php b/wp-includes/default-widgets.php
index b0867556d1..817181a002 100644
--- a/wp-includes/default-widgets.php
+++ b/wp-includes/default-widgets.php
@@ -472,9 +472,9 @@ class WP_Widget_Categories extends WP_Widget {
 	function update( $new_instance, $old_instance ) {
 		$instance = $old_instance;
 		$instance['title'] = strip_tags($new_instance['title']);
-		$instance['count'] = $new_instance['count'] ? 1 : 0;
-		$instance['hierarchical'] = $new_instance['hierarchical'] ? 1 : 0;
-		$instance['dropdown'] = $new_instance['dropdown'] ? 1 : 0;
+		$instance['count'] = !empty($new_instance['count']) ? 1 : 0;
+		$instance['hierarchical'] = !empty($new_instance['hierarchical']) ? 1 : 0;
+		$instance['dropdown'] = !empty($new_instance['dropdown']) ? 1 : 0;
 
 		return $instance;
 	}
@@ -739,7 +739,7 @@ class WP_Widget_RSS extends WP_Widget {
 	}
 
 	function update($new_instance, $old_instance) {
-		$testurl = $new_instance['url'] != $old_instance['url'];
+		$testurl = ( isset($new_instance['url']) && ($new_instance['url'] != $old_instance['url']) );
 		return wp_widget_rss_process( $new_instance, $testurl );
 	}
 
@@ -939,9 +939,9 @@ function wp_widget_rss_process( $widget_rss, $check_feed = true ) {
 		$items = 10;
 	$url           = esc_url_raw(strip_tags( $widget_rss['url'] ));
 	$title         = trim(strip_tags( $widget_rss['title'] ));
-	$show_summary  = (int) $widget_rss['show_summary'];
-	$show_author   = (int) $widget_rss['show_author'];
-	$show_date     = (int) $widget_rss['show_date'];
+	$show_summary  = isset($widget_rss['show_summary']) ? (int) $widget_rss['show_summary'] : 0;
+	$show_author   = isset($widget_rss['show_author']) ? (int) $widget_rss['show_author'] :0;
+	$show_date     = isset($widget_rss['show_date']) ? (int) $widget_rss['show_date'] : 0;
 
 	if ( $check_feed ) {
 		$rss = fetch_feed($url);
diff --git a/wp-includes/general-template.php b/wp-includes/general-template.php
index 7ddc13d622..f6fc51af31 100644
--- a/wp-includes/general-template.php
+++ b/wp-includes/general-template.php
@@ -152,7 +152,7 @@ function wp_loginout($redirect = '', $echo = true) {
 		$link = '<a href="' . esc_url( wp_login_url($redirect) ) . '">' . __('Log in') . '</a>';
 	else
 		$link = '<a href="' . esc_url( wp_logout_url($redirect) ) . '">' . __('Log out') . '</a>';
-	
+
 	if ( $echo )
 		echo apply_filters('loginout', $link);
 	else
@@ -300,7 +300,7 @@ function wp_register( $before = '<li>', $after = '</li>', $echo = true ) {
 	} else {
 		$link = $before . '<a href="' . admin_url() . '">' . __('Site Admin') . '</a>' . $after;
 	}
-	
+
 	if ( $echo )
 		echo apply_filters('register', $link);
 	else
@@ -1021,11 +1021,11 @@ function get_calendar($initial = true, $echo = true) {
 	$cache = array();
 	$key = md5( $m . $monthnum . $year );
 	if ( $cache = wp_cache_get( 'get_calendar', 'calendar' ) ) {
-		if ( is_array($cache) && isset( $cache[ $key ] ) ) {		
+		if ( is_array($cache) && isset( $cache[ $key ] ) ) {
 			if ( $echo )
 				echo apply_filters( 'get_calendar',  $cache[$key] );
 			else
-				return apply_filters( 'get_calendar',  $cache[$key] );	
+				return apply_filters( 'get_calendar',  $cache[$key] );
 		}
 	}
 
@@ -1087,7 +1087,7 @@ function get_calendar($initial = true, $echo = true) {
 
 	/* translators: Calendar caption: 1: month name, 2: 4-digit year */
 	$calendar_caption = _x('%1$s %2$s', 'calendar caption');
-	$calendar_output .= '<table id="wp-calendar" summary="' . esc_attr__('Calendar') . '">
+	$calendar_output = '<table id="wp-calendar" summary="' . esc_attr__('Calendar') . '">
 	<caption>' . sprintf($calendar_caption, $wp_locale->get_month($thismonth), date('Y', $unixmonth)) . '</caption>
 	<thead>
 	<tr>';
@@ -1103,7 +1103,7 @@ function get_calendar($initial = true, $echo = true) {
 		$wd = esc_attr($wd);
 		$calendar_output .= "\n\t\t<th scope=\"col\" title=\"$wd\">$day_name</th>";
 	}
-	
+
 	$calendar_output .= '
 	</tr>
 	</thead>
@@ -1206,7 +1206,7 @@ function get_calendar($initial = true, $echo = true) {
 
 	$calendar_output .= "\n\t</tr>\n\t</tbody>\n\t</table>";
 
-	$cache[ $key ] = $output;
+	$cache[ $key ] = $calendar_output;
 	wp_cache_set( 'get_calendar', $cache, 'calendar' );
 
 	if ( $echo )