diff --git a/source/mijin/util/exception.hpp b/source/mijin/util/exception.hpp
index 1f0b776..1688189 100644
--- a/source/mijin/util/exception.hpp
+++ b/source/mijin/util/exception.hpp
@@ -42,7 +42,7 @@ public:
 // public functions
 //
 
-template<typename TCondition, typename TException = std::runtime_error, typename... TExceptionArgs>
+template<typename TCondition, typename TException = Exception, typename... TExceptionArgs>
 inline decltype(auto) ensure(TCondition&& condition, TExceptionArgs&&... args)
 {
     if (!static_cast<bool>(std::forward<TCondition>(condition)))