diff --git a/agents.py b/agents.py
index cd5f0b865..21dedaa15 100644
--- a/agents.py
+++ b/agents.py
@@ -35,7 +35,7 @@
 #
 # Speed control in GUI does not have any effect -- fix it.
 
-from grid import distance2
+from grid import distance2, turn_heading
 from statistics import mean
 
 import random