diff --git a/src/wp-includes/class-wp-comment.php b/src/wp-includes/class-wp-comment.php
index 996815939dfd0..c7c5227595f8d 100644
--- a/src/wp-includes/class-wp-comment.php
+++ b/src/wp-includes/class-wp-comment.php
@@ -359,6 +359,8 @@ public function __isset( $name ) {
 			$post = get_post( $this->comment_post_ID );
 			return property_exists( $post, $name );
 		}
+
+		return false;
 	}
 
 	/**
diff --git a/src/wp-includes/class-wp-query.php b/src/wp-includes/class-wp-query.php
index d25493dc5c4e1..bc673191a8a16 100644
--- a/src/wp-includes/class-wp-query.php
+++ b/src/wp-includes/class-wp-query.php
@@ -4011,6 +4011,8 @@ public function __isset( $name ) {
 		if ( in_array( $name, $this->compat_fields, true ) ) {
 			return isset( $this->$name );
 		}
+
+		return false;
 	}
 
 	/**