diff --git a/pylib/geometry.py b/pylib/geometry.py
index 41f1be8..e14df30 100644
--- a/pylib/geometry.py
+++ b/pylib/geometry.py
@@ -12,7 +12,7 @@
 """
 import math
 import copy
-from mathematics import vector, matrix
+from pylib.mathematics import vector, matrix
 
 class Direction(vector):
   """Direction in local coordinate system"""