Index: wp-includes/bookmark.php
===================================================================
--- wp-includes/bookmark.php	(revision 5241)
+++ wp-includes/bookmark.php	(working copy)
@@ -136,7 +136,7 @@
 	$results = $wpdb->get_results($query);
 
 	$cache[ $key ] = $results;
-	wp_cache_set( 'get_bookmarks', $cache, 'bookmark' );
+	wp_cache_add( 'get_bookmarks', $cache, 'bookmark' );
 
 	return apply_filters('get_bookmarks', $results, $r);
 }
Index: wp-includes/category.php
===================================================================
--- wp-includes/category.php	(revision 5241)
+++ wp-includes/category.php	(working copy)
@@ -8,7 +8,7 @@
 
 	if ( ! $cat_ids = wp_cache_get('all_category_ids', 'category') ) {
 		$cat_ids = $wpdb->get_col("SELECT cat_ID FROM $wpdb->categories");
-		wp_cache_set('all_category_ids', $cat_ids, 'category');
+		wp_cache_add('all_category_ids', $cat_ids, 'category');
 	}
 
 	return $cat_ids;
@@ -139,7 +139,7 @@
 	reset ( $categories );
 
 	$cache[ $key ] = $categories;
-	wp_cache_set( 'get_categories', $cache, 'category' );
+	wp_cache_add( 'get_categories', $cache, 'category' );
 
 	$categories = apply_filters('get_categories', $categories, $r);
 	return $categories;
@@ -160,7 +160,7 @@
 		$category = (int) $category;
 		if ( ! $_category = wp_cache_get($category, 'category') ) {
 			$_category = $wpdb->get_row("SELECT * FROM $wpdb->categories WHERE cat_ID = '$category' LIMIT 1");
-			wp_cache_set($category, $_category, 'category');
+			wp_cache_add($category, $_category, 'category');
 		}
 	}
 
Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 5243)
+++ wp-includes/post.php	(working copy)
@@ -1012,7 +1012,7 @@
 
 	if ( ! $page_ids = wp_cache_get('all_page_ids', 'pages') ) {
 		$page_ids = $wpdb->get_col("SELECT ID FROM $wpdb->posts WHERE post_type = 'page'");
-		wp_cache_set('all_page_ids', $page_ids, 'pages');
+		wp_cache_add('all_page_ids', $page_ids, 'pages');
 	}
 
 	return $page_ids;
@@ -1055,7 +1055,7 @@
 					return get_post($_page, $output);
 				// Potential issue: we're not checking to see if the post_type = 'page'
 				// So all non-'post' posts will get cached as pages.
-				wp_cache_set($_page->ID, $_page, 'pages');
+				wp_cache_add($_page->ID, $_page, 'pages');
 			}
 		}
 	}
Index: wp-includes/general-template.php
===================================================================
--- wp-includes/general-template.php	(revision 5241)
+++ wp-includes/general-template.php	(working copy)
@@ -635,7 +635,7 @@
 	ob_end_clean();
 	echo $output;
 	$cache[ $key ] = $output;
-	wp_cache_set( 'get_calendar', $cache, 'calendar' );
+	wp_cache_add( 'get_calendar', $cache, 'calendar' );
 }
 
 function delete_get_calendar_cache() {
Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 5241)
+++ wp-includes/functions.php	(working copy)
@@ -229,7 +229,7 @@
 
 			if( is_object( $row) ) { // Has to be get_row instead of get_var because of funkiness with 0, false, null values
 				$value = $row->option_value;
-				wp_cache_set($setting, $value, 'options');
+				wp_cache_add($setting, $value, 'options');
 			} else { // option does not exist, so we must cache its non-existence
 				$notoptions[$setting] = true;
 				wp_cache_set('notoptions', $notoptions, 'options');
@@ -294,7 +294,7 @@
 		$alloptions = array();
 		foreach ( (array) $alloptions_db as $o )
 			$alloptions[$o->option_name] = $o->option_value;
-		wp_cache_set('alloptions', $alloptions, 'options');
+		wp_cache_add('alloptions', $alloptions, 'options');
 	}
 	return $alloptions;
 }