diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index 2a02400bd1..3042ec7ddc 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -5165,7 +5165,11 @@ function wp_unique_post_slug( $slug, $post_id, $post_status, $post_type, $post_p
 		 * Page slugs must be unique within their own trees. Pages are in a separate
 		 * namespace than posts so page slugs are allowed to overlap post slugs.
 		 */
-		$check_sql       = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( %s, 'attachment' ) AND ID != %d AND post_parent = %d LIMIT 1";
+		if ( 'page' === $post_type ) {
+			$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( %s, 'post', 'attachment' ) AND ID != %d AND post_parent = %d LIMIT 1";
+		} else {
+			$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( %s, 'attachment' ) AND ID != %d AND post_parent = %d LIMIT 1";
+		}
 		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_id, $post_parent ) );
 
 		/**
@@ -5195,7 +5199,11 @@ function wp_unique_post_slug( $slug, $post_id, $post_status, $post_type, $post_p
 		}
 	} else {
 		// Post slugs must be unique across all posts.
-		$check_sql       = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type = %s AND ID != %d LIMIT 1";
+		if ( 'post' === $post_type ) {
+			$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN( %s, 'page' ) AND ID != %d LIMIT 1";
+		} else {
+			$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type = %s AND ID != %d LIMIT 1";
+		}
 		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_id ) );
 
 		$post = get_post( $post_id );