diff --git a/includes/Commission.php b/includes/Commission.php
index 9490e787f5..edaf94e4fe 100644
--- a/includes/Commission.php
+++ b/includes/Commission.php
@@ -287,7 +287,7 @@ public function get_earning_by_order( $order, $context = 'seller' ) {
      */
     public function validate_rate( $rate ) {
         if ( '' === $rate || ! is_numeric( $rate ) || $rate < 0 ) {
-            return null;
+            $rate = 0.0;
         }
 
         return (float) $rate;