diff --git a/SqlBuilder.php b/SqlBuilder.php
index dc4885a..55e64d7 100644
--- a/SqlBuilder.php
+++ b/SqlBuilder.php
@@ -189,7 +189,7 @@ class SqlBuilder extends Component
         if (is_null($value)) {
             return $keys;
         }
-        if ($this->isMath($value)) {
+        if (preg_match('/^[+|-]\s\d+$/', $value)) {
             $keys[] = $key . '=' . $key . ' ' . $value;
         } else {
             $this->query->pushParam($value);
@@ -199,16 +199,6 @@ class SqlBuilder extends Component
     }
 
 
-    /**
-     * @param string $value
-     * @return bool
-     */
-    private function isMath(string $value): bool
-    {
-		return (bool)preg_match('/^[+|-]\s\d+$/', $value);
-    }
-
-
     /**
      * @return string
      * @throws