diff --git a/src/parser/cxx/parser.cc b/src/parser/cxx/parser.cc
index 59ec7a9a..afc2e7b8 100644
--- a/src/parser/cxx/parser.cc
+++ b/src/parser/cxx/parser.cc
@@ -3005,6 +3005,8 @@ auto Parser::parse_conditional_expression(ExpressionAST*& yyast,
   SourceLocation questionLoc;
   if (!match(TokenKind::T_QUESTION, questionLoc)) return true;
 
+  check_bool_condition(yyast);
+
   auto ast = make_node<ConditionalExpressionAST>(pool_);
   ast->condition = yyast;
   ast->questionLoc = questionLoc;