diff --git a/win/rfb_win32/Clipboard.cxx b/win/rfb_win32/Clipboard.cxx
index a4c43f0..482519e 100644
--- a/win/rfb_win32/Clipboard.cxx
+++ b/win/rfb_win32/Clipboard.cxx
@@ -185,7 +185,7 @@
 
     vlog.debug("set clipboard");
   } catch (rdr::Exception& e) {
-    vlog.debug(e.str());
+    vlog.debug("%s", e.str());
   }
 
   // - Close the clipboard