diff --git a/vncviewer/Viewport.cxx b/vncviewer/Viewport.cxx
index 027ca54..917a981 100644
--- a/vncviewer/Viewport.cxx
+++ b/vncviewer/Viewport.cxx
@@ -1025,6 +1025,10 @@
 {
   rdr::U32 keySym;
 
+#ifdef HAVE_FLTK_XHANDLERS
+  return;
+#endif
+
   keySym = translateKeyEvent();
   if (keySym == NoSymbol)
     return;