diff --git a/parser/parser.yy b/parser/parser.yy
index 4c931e4..eed22a4 100644
--- a/parser/parser.yy
+++ b/parser/parser.yy
@@ -408,6 +408,9 @@ bool_expression: expression LESS expression {
                | NOT bool_expression {
                     $$ = new BoolExpressionNode('!', $2, NULL);
                }
+               | LPAREN bool_expression RPAREN {
+                    $$ = $2;
+               }
                ;
 
 assignment: VARREF ASSIGN expression {