class PyFlexGridSizer(PyGridSizer):
     def __init__(self, rows=0, cols=0, hgap=0, vgap=0):
-        wxGridSizer.__init__(self, rows, cols, hgap, vgap)
+        PyGridSizer.__init__(self, rows, cols, hgap, vgap)
         self.rowHeights = []
         self.colWidths  = []
         self.growableRows = []