diff --git a/src/playbin.vala b/src/playbin.vala
index afb1e87..c0fc546 100644
--- a/src/playbin.vala
+++ b/src/playbin.vala
@@ -85,7 +85,10 @@ public class Playbin : GLib.Object {
 
         this.mpv.wakeup_callback = () => {
             Idle.add (() => {
-                if (this.is_handling_event) return false;
+                if (this.is_handling_event) {
+                    warning ("main thread mpv wakeup callback called twice");
+                    return false;
+                }
                 this.is_handling_event = true;
 
                 while (true) {