- Some more work done to allow more flexibility for other plugins

src/Query/Where.php

@@ -114,7 +114,7 @@ class Where extends Fragment {
                 }
 
                 # whitelisting operators
-                return in_array(strtoupper($this->operator), [ '=', '!=', '<>', 'LIKE' ]) ? $this->operator : "=";
+                return in_array(strtoupper($this->operator), [ '=', '!=', '<>', 'LIKE', 'IS', 'IS NOT' ]) ? $this->operator : "=";
             }
 
             protected function value()