diff --git a/io/HeaderVal.hpp b/io/HeaderVal.hpp
index 12802f418d..af4feb3c63 100644
--- a/io/HeaderVal.hpp
+++ b/io/HeaderVal.hpp
@@ -49,7 +49,7 @@ class BaseHeaderVal
     BaseHeaderVal() : m_val(T()), m_valSet(false)
     {}
 
-    BaseHeaderVal(const T& t) : m_defVal(t), m_valSet(false)
+    BaseHeaderVal(const T& t) : m_val(T()), m_defVal(t), m_valSet(false)
     {}
 
 public: