diff --git a/wp-includes/post.php b/wp-includes/post.php
index 8f08b0d3d5..c1dfd168d9 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -3494,7 +3494,7 @@ function get_pages($args = '') {
 	$cache = array();
 	$key = md5( serialize( compact(array_keys($defaults)) ) );
 	if ( $cache = wp_cache_get( 'get_pages', 'posts' ) ) {
-		if ( is_array($cache) && isset( $cache[ $key ] ) ) {
+		if ( is_array($cache) && isset( $cache[ $key ] ) && is_array( $cache[ $key ] ) ) {
 			// Convert to WP_Post instances
 			$pages = array_map( 'get_post', $cache[ $key ] );
 			$pages = apply_filters( 'get_pages', $pages, $r );