diff --git a/include/wx/convauto.h b/include/wx/convauto.h
index 1e32c72c07..89682525ef 100644
--- a/include/wx/convauto.h
+++ b/include/wx/convauto.h
@@ -27,7 +27,7 @@ public:
 
     // copy ctor doesn't initialize anything neither as conversion can only be
     // deduced on first use
-    wxConvAuto(const wxConvAuto& WXUNUSED(other)) { m_conv = NULL; }
+    wxConvAuto(const wxConvAuto& WXUNUSED(other)) : wxMBConv() { m_conv = NULL; }
 
     virtual ~wxConvAuto() { if ( m_conv && m_ownsConv ) delete m_conv; }
 
diff --git a/include/wx/strconv.h b/include/wx/strconv.h
index 134434405a..e2ef14a6ba 100644
--- a/include/wx/strconv.h
+++ b/include/wx/strconv.h
@@ -191,7 +191,8 @@ class WXDLLIMPEXP_BASE wxConvBrokenFileNames : public wxMBConv
 public:
     wxConvBrokenFileNames(const wxChar *charset);
     wxConvBrokenFileNames(const wxConvBrokenFileNames& conv)
-        : m_conv(conv.m_conv ? conv.m_conv->Clone() : NULL)
+        : wxMBConv(),
+          m_conv(conv.m_conv ? conv.m_conv->Clone() : NULL)
     {
     }
     virtual ~wxConvBrokenFileNames() { delete m_conv; }