diff --git a/handlers/views_handler_filter_boolean_operator.inc b/handlers/views_handler_filter_boolean_operator.inc
index c2ec624..c03ee8c 100644
--- a/handlers/views_handler_filter_boolean_operator.inc
+++ b/handlers/views_handler_filter_boolean_operator.inc
@@ -141,17 +141,17 @@ class views_handler_filter_boolean_operator extends views_handler_filter {
     $where = "$this->table_alias.$this->real_field ";
 
     if (empty($this->value)) {
-      $where .= '= 0';
+      $where .= "= '0'";
       if ($this->accept_null) {
         $where = '(' . $where . " OR $this->table_alias.$this->real_field IS NULL)";
       }
     }
     else {
       if (!empty($this->definition['use equal'])) {
-        $where .= '= 1';
+        $where .= "= '1'";
       }
       else {
-        $where .= '<> 0';
+        $where .= "<> '0'";
       }
     }
     $this->query->add_where($this->options['group'], $where);