diff --git a/vncviewer/DesktopWindow.cxx b/vncviewer/DesktopWindow.cxx
index 17be6e0..e8750b4 100644
--- a/vncviewer/DesktopWindow.cxx
+++ b/vncviewer/DesktopWindow.cxx
@@ -761,6 +761,23 @@
     fullscreen();
 }
 
+#if !defined(WIN32) && !defined(__APPLE__)
+Bool eventIsFocusWithSerial(Display *display, XEvent *event, XPointer arg)
+{
+  unsigned long serial;
+
+  serial = *(unsigned long*)arg;
+
+  if (event->xany.serial != serial)
+    return False;
+
+  if ((event->type != FocusIn) && (event->type != FocusOut))
+    return False;
+
+  return True;
+}
+#endif
+
 void DesktopWindow::grabKeyboard()
 {
   // Grabbing the keyboard is fairly safe as FLTK reroutes events to the
@@ -788,6 +805,11 @@
 #else
   int ret;
 
+  XEvent xev;
+  unsigned long serial;
+
+  serial = XNextRequest(fl_display);
+
   ret = XGrabKeyboard(fl_display, fl_xid(this), True,
                       GrabModeAsync, GrabModeAsync, CurrentTime);
   if (ret) {
@@ -801,6 +823,16 @@
     }
     return;
   }
+
+  // Xorg 1.20+ generates FocusIn/FocusOut even when there is no actual
+  // change of focus. This causes us to get stuck in an endless loop
+  // grabbing and ungrabbing the keyboard. Avoid this by filtering out
+  // any focus events generated by XGrabKeyboard().
+  XSync(fl_display, False);
+  while (XCheckIfEvent(fl_display, &xev, &eventIsFocusWithSerial,
+                       (XPointer)&serial) == True) {
+    vlog.debug("Ignored synthetic focus event cause by grab change");
+  }
 #endif
 
   keyboardGrabbed = true;
@@ -827,7 +859,19 @@
   if (Fl::grab())
     return;
 
+  XEvent xev;
+  unsigned long serial;
+
+  serial = XNextRequest(fl_display);
+
   XUngrabKeyboard(fl_display, CurrentTime);
+
+  // See grabKeyboard()
+  XSync(fl_display, False);
+  while (XCheckIfEvent(fl_display, &xev, &eventIsFocusWithSerial,
+                       (XPointer)&serial) == True) {
+    vlog.debug("Ignored synthetic focus event cause by grab change");
+  }
 #endif
 }