diff --git a/src/lib/base/XBase.cpp b/src/lib/base/XBase.cpp
index 123fb297..1c776bcd 100644
--- a/src/lib/base/XBase.cpp
+++ b/src/lib/base/XBase.cpp
@@ -48,7 +48,8 @@ XBase::what() const _NOEXCEPT
 {
 	const char* what = std::runtime_error::what();
 	if (strlen(what) == 0) {
-		return getWhat().c_str();
+		m_what = getWhat();
+		return m_what.c_str();
 	}
 	return what;
 }
diff --git a/src/lib/base/XBase.h b/src/lib/base/XBase.h
index 5e576aec..b3688436 100644
--- a/src/lib/base/XBase.h
+++ b/src/lib/base/XBase.h
@@ -48,6 +48,8 @@ protected:
 	*/
 	virtual CString		format(const char* id,
 							const char* defaultFormat, ...) const throw();
+private:
+	mutable CString		m_what;
 };
 
 /*!