diff --git a/src/common/msgout.cpp b/src/common/msgout.cpp
index 07889dbc59..804bec9b47 100644
--- a/src/common/msgout.cpp
+++ b/src/common/msgout.cpp
@@ -147,6 +147,8 @@ void wxMessageOutputStderr::Output(const wxString& str)
         fprintf(m_fp, "%s", (const char*) buf);
     else // print at least something
         fprintf(m_fp, "%s", (const char*) strWithLF.ToAscii());
+
+    fflush(m_fp);
 }
 
 // ----------------------------------------------------------------------------