Fix unsafe format strings to the logging functions
diff --git a/win/winvnc/VNCServerWin32.cxx b/win/winvnc/VNCServerWin32.cxx
index b1b9596..36dbcee 100644
--- a/win/winvnc/VNCServerWin32.cxx
+++ b/win/winvnc/VNCServerWin32.cxx
@@ -189,10 +189,10 @@
 
     vlog.debug("Server exited cleanly");
   } catch (rdr::SystemException &s) {
-    vlog.error(s.str());
+    vlog.error("%s", s.str());
     result = s.err;
   } catch (rdr::Exception &e) {
-    vlog.error(e.str());
+    vlog.error("%s", e.str());
   }
 
   { Lock l(runLock);