diff --git a/wxPython/wx/lib/customtreectrl.py b/wxPython/wx/lib/customtreectrl.py
index 842ebe5e24..37949d0400 100644
--- a/wxPython/wx/lib/customtreectrl.py
+++ b/wxPython/wx/lib/customtreectrl.py
@@ -2373,7 +2373,7 @@ class CustomTreeCtrl(wx.PyScrolledWindow):
         return item.GetText()
     
 
-    def GetItemImage(self, item, which):
+    def GetItemImage(self, item, which=TreeItemIcon_Normal):
         """Returns the item image."""
 
         if not item:
@@ -5747,4 +5747,4 @@ class CustomTreeCtrl(wx.PyScrolledWindow):
 
     GetClassDefaultAttributes = classmethod(GetClassDefaultAttributes)
 
-    
\ No newline at end of file
+