diff --git a/pyglet/gui/widgets.py b/pyglet/gui/widgets.py
index 4ba66dd0..94513af2 100644
--- a/pyglet/gui/widgets.py
+++ b/pyglet/gui/widgets.py
@@ -265,7 +265,7 @@ class PushButton(WidgetBase):
             return
         self._sprite.image = self._unpressed_img
         self._pressed = False
-        self.dispatch_event('on_release')
+        self.dispatch_event('on_release', self)

     def on_mouse_motion(self, x: int, y: int, dx: int, dy: int) -> None:
         if not self.enabled or self._pressed: