diff --git a/hw/xquartz/X11Application.m b/hw/xquartz/X11Application.m
index 9f4c9b71e..1f9b05dd1 100644
--- a/hw/xquartz/X11Application.m
+++ b/hw/xquartz/X11Application.m
@@ -1329,6 +1329,11 @@ untrusted_str(NSEvent *e)
 }
 #endif
 
+extern void
+darwinEvents_lock(void);
+extern void
+darwinEvents_unlock(void);
+
 - (void) sendX11NSEvent:(NSEvent *)e
 {
     NSPoint location = NSZeroPoint;
@@ -1341,18 +1346,15 @@ untrusted_str(NSEvent *e)
     int modifierFlags;
     BOOL isMouseOrTabletEvent, isTabletEvent;
 
-#ifdef HAVE_LIBDISPATCH
-    static dispatch_once_t once_pred;
-    dispatch_once(&once_pred, ^{
-                      tilt = NSZeroPoint;
-                      darwinTabletCurrent = darwinTabletStylus;
-                  });
-#else
     if (!darwinTabletCurrent) {
+        /* Ensure that the event system is initialized */
+        darwinEvents_lock();
+        darwinEvents_unlock();
+        assert(darwinTabletStylus);
+
         tilt = NSZeroPoint;
         darwinTabletCurrent = darwinTabletStylus;
     }
-#endif
 
     isMouseOrTabletEvent = [e type] == NSLeftMouseDown ||
                            [e type] == NSOtherMouseDown ||