diff --git a/src/common/msgout.cpp b/src/common/msgout.cpp
index da9af7b1d9..d2d1c530a4 100644
--- a/src/common/msgout.cpp
+++ b/src/common/msgout.cpp
@@ -140,12 +140,13 @@ wxString wxMessageOutputStderr::AppendLineFeedIfNeeded(const wxString& str)
 
 void wxMessageOutputStderr::Output(const wxString& str)
 {
-    const wxWX2MBbuf buf = AppendLineFeedIfNeeded(str).mb_str();
+    const wxString strWithLF = AppendLineFeedIfNeeded(str);
+    const wxWX2MBbuf buf = strWithLF.mb_str();
 
     if ( buf )
         fprintf(stderr, "%s", (const char*) buf);
     else // print at least something
-        fprintf(stderr, "%s", (const char*) str.ToAscii());
+        fprintf(stderr, "%s", (const char*) strWithLF.ToAscii());
 }
 
 // ----------------------------------------------------------------------------