diff --git a/src/common/log.cpp b/src/common/log.cpp
index 653c35cc3b..838e526a7e 100644
--- a/src/common/log.cpp
+++ b/src/common/log.cpp
@@ -1075,9 +1075,11 @@ static const wxChar* GetSysErrorMsg(wxChar* szBuf, size_t sizeBuf, unsigned long
             NULL
          ) == 0 )
     {
+        wxLogDebug(wxS("FormatMessage failed with error 0x%lx in %s"),
+            GetLastError(), __WXFUNCTION__ ? __WXFUNCTION__ : "");
         // if this happens, something is seriously wrong, so don't use _() here
         // for safety
-        wxSprintf(szBuf, wxS("unknown error %lx"), nErrCode);
+        wxSprintf(szBuf, wxS("unknown error 0x%lx"), nErrCode);
         return szBuf;
     }