diff --git a/pptx/oxml/shapes/groupshape.py b/pptx/oxml/shapes/groupshape.py
index 9484ab58c..d1c78da0c 100644
--- a/pptx/oxml/shapes/groupshape.py
+++ b/pptx/oxml/shapes/groupshape.py
@@ -81,7 +81,7 @@ def add_custom_geometry(self, id_, name, left, top, width, height):
         Append a newly-created custom geometry shape with the specified
         position and size.
         """
-        sp = CT_Shape.new_custom_geometry_shape_sp(id_, name, left, top, width, height)
+        sp = CT_Shape.new_custom_geometry_sp(id_, name, left, top, width, height)
         self.insert_element_before(sp, 'p:extList')
         return sp