diff --git a/wxPython/wxPython/lib/throbber.py b/wxPython/wxPython/lib/throbber.py
index acb4a77361..f7de6044c9 100644
--- a/wxPython/wxPython/lib/throbber.py
+++ b/wxPython/wxPython/lib/throbber.py
@@ -217,6 +217,8 @@ class Throbber(wxPanel):
 
     def Stop(self):
         """Stop the animation"""
+        if self.event.isSet():
+            return
         self.event.set()