diff --git a/gramps/gui/widgets/fanchartdesc.py b/gramps/gui/widgets/fanchartdesc.py
index 0c250f3ed..371595c2f 100644
--- a/gramps/gui/widgets/fanchartdesc.py
+++ b/gramps/gui/widgets/fanchartdesc.py
@@ -535,6 +535,7 @@ class FanChartDescWidget(FanChartBaseWidget):
         elif nrparent <= 4:
             angleinc = math.pi/2
         else:
+            # FIXME: nrchild not set
             angleinc = 2 * math.pi / nrchild
         for data in self.innerring:
             self.draw_innerring(cr, data[0], data[1], startangle, angleinc)