diff --git a/includes/form.inc b/includes/form.inc
index 039f73719b7913a26ddacd47ee3409b82c367c34..ea39411bd54baea2870a43bf5179df4337897a50 100644
--- a/includes/form.inc
+++ b/includes/form.inc
@@ -114,7 +114,7 @@ function drupal_validate_form($form_id, &$form, $callback = NULL) {
   if (function_exists($form_id . '_validate')) {
     call_user_func($form_id . '_validate', $form_id, $form_values);
   }
-  if (function_exists($callback . '_validate')) {
+  elseif (function_exists($callback . '_validate')) {
     call_user_func($callback . '_validate', $form_id, $form_values);
   }
 }