diff --git a/ConstantExpression.cpp b/ConstantExpression.cpp
index 8a2b875..97e1317 100644
--- a/ConstantExpression.cpp
+++ b/ConstantExpression.cpp
@@ -435,7 +435,7 @@
 
 #define CASE_STR(__type__) return std::to_string(this->cast<__type__>());
 
-    SWITCH_KIND(castKind, CASE_STR, SHOULD_NOT_REACH(); return 0; );
+    SWITCH_KIND(castKind, CASE_STR, SHOULD_NOT_REACH(); return nullptr; );
 }
 
 template<typename T>