diff --git a/login_security.module b/login_security.module
index 7887175..257d860 100644
--- a/login_security.module
+++ b/login_security.module
@@ -89,10 +89,18 @@ function login_security_form_alter(&$form, $form_state, $form_id) {
       // Put login_security first or the capture of the previous login timestamp won't work
       // and core's validation will update to the current login instance before login_security
       // can read the old timestamp.
-      $form['#validate'] = array_merge(array('login_security_soft_block_validate', 'login_security_set_login_timestamp'), $form['#validate']);
+      $validate = array('login_security_soft_block_validate', 'login_security_set_login_timestamp');
+      
+      if (isset($form['#validate']) && is_array($form['#validate'])) {
+        $form['#validate'] = array_merge($validate, $form['#validate']);
+      }
+      else {
+        $form['#validate'] = $validate;
+      }
+      
       $form['#validate'][] = 'login_security_validate';
       break;
-      }
+    }
   }
 
  /**