diff --git a/include/wx/defs.h b/include/wx/defs.h
index 00c6427636..203e0f77eb 100644
--- a/include/wx/defs.h
+++ b/include/wx/defs.h
@@ -310,8 +310,10 @@ typedef short int WXTYPE;
     inline T wx_truncate_cast_impl(X x)
     {
         #pragma warning(push)
-        /* conversion from 'X' to 'T', possible loss of data */
+        /* conversion from 'size_t' to 'type', possible loss of data */
         #pragma warning(disable: 4267)
+        /* conversion from 'type1' to 'type2', possible loss of data */
+        #pragma warning(disable: 4242)
 
         return x;
 
diff --git a/include/wx/strvararg.h b/include/wx/strvararg.h
index dc566e9443..6562ee3150 100644
--- a/include/wx/strvararg.h
+++ b/include/wx/strvararg.h
@@ -748,7 +748,7 @@ struct wxArgNormalizer<const wxUniChar&> : public wxArgNormalizer<wchar_t>
 {
     wxArgNormalizer(const wxUniChar& s,
                     const wxFormatString *fmt, unsigned index)
-        : wxArgNormalizer<wchar_t>(s.GetValue(), fmt, index) {}
+        : wxArgNormalizer<wchar_t>(wx_truncate_cast(wchar_t, s.GetValue()), fmt, index) {}
 };
 
 // for wchar_t, default handler does the right thing
diff --git a/include/wx/unichar.h b/include/wx/unichar.h
index a661e5a4e2..e9726943ab 100644
--- a/include/wx/unichar.h
+++ b/include/wx/unichar.h
@@ -161,7 +161,7 @@ private:
 
         return ToHi8bit(c);
 #else
-        return c;
+        return wx_truncate_cast(char, c);
 #endif
     }