diff --git a/src/wp-includes/class-wp-query.php b/src/wp-includes/class-wp-query.php
index 21127dc755f1c..7092d0cb7a20a 100644
--- a/src/wp-includes/class-wp-query.php
+++ b/src/wp-includes/class-wp-query.php
@@ -2882,7 +2882,7 @@ public function get_posts() {
 			$comments_request = "SELECT $distinct {$wpdb->comments}.comment_ID FROM {$wpdb->comments} $cjoin $cwhere $cgroupby $corderby $climits";
 
 			$key          = md5( $comments_request );
-			$last_changed = wp_cache_get_last_changed( 'comment' ) . ':' . wp_cache_get_last_changed( 'posts' );
+			$last_changed = wp_cache_get_last_changed( 'comment' ) . '+' . wp_cache_get_last_changed( 'posts' );
 
 			$cache_key   = "comment_feed:$key:$last_changed";
 			$comment_ids = wp_cache_get( $cache_key, 'comment-queries' );
@@ -5064,7 +5064,7 @@ static function ( &$value ) use ( $wpdb, $placeholder ) {
 
 		$last_changed = wp_cache_get_last_changed( 'posts' );
 		if ( ! empty( $this->tax_query->queries ) ) {
-			$last_changed .= wp_cache_get_last_changed( 'terms' );
+			$last_changed .= '+' . wp_cache_get_last_changed( 'terms' );
 		}
 
 		$this->query_cache_key = "wp_query:$key:$last_changed";
diff --git a/src/wp-includes/class-wp-user-query.php b/src/wp-includes/class-wp-user-query.php
index fd35182eab9f5..ff7afaa400ada 100644
--- a/src/wp-includes/class-wp-user-query.php
+++ b/src/wp-includes/class-wp-user-query.php
@@ -1080,7 +1080,7 @@ protected function generate_cache_key( array $args, $sql ) {
 				switch_to_blog( $blog_id );
 			}
 
-			$last_changed .= wp_cache_get_last_changed( 'posts' );
+			$last_changed .= '+' . wp_cache_get_last_changed( 'posts' );
 
 			if ( $switch ) {
 				restore_current_blog();
diff --git a/src/wp-includes/link-template.php b/src/wp-includes/link-template.php
index 24c713d89dbd4..c7aea8d60a02b 100644
--- a/src/wp-includes/link-template.php
+++ b/src/wp-includes/link-template.php
@@ -2007,7 +2007,7 @@ function get_adjacent_post( $in_same_term = false, $excluded_terms = '', $previo
 	$key          = md5( $query );
 	$last_changed = wp_cache_get_last_changed( 'posts' );
 	if ( $in_same_term || ! empty( $excluded_terms ) ) {
-		$last_changed .= wp_cache_get_last_changed( 'terms' );
+		$last_changed .= '+' . wp_cache_get_last_changed( 'terms' );
 	}
 	$cache_key = "adjacent_post:$key:$last_changed";