diff --git a/Lib/fontTools/ttLib/tables/_g_l_y_f.py b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
index bc3bb5ea0..440d3f957 100644
--- a/Lib/fontTools/ttLib/tables/_g_l_y_f.py
+++ b/Lib/fontTools/ttLib/tables/_g_l_y_f.py
@@ -474,7 +474,7 @@ class Glyph:
 		nCoordinates = len(self.coordinates)
 		
 		# make a copy
-		coordinates = self.coordinates.astype(self.coordinates.typecode())
+		coordinates = numpy.array(self.coordinates)
 		# absolute to relative coordinates
 		coordinates[1:] = numpy.subtract(coordinates[1:], coordinates[:-1])
 		flags = self.flags