diff --git a/tests/test_rendertools.py b/tests/test_rendertools.py
index 427ff2f70b12e7f2f1f51f5ed4960b549470e739..0f7e1a002005663e3962da755235bf7567171b4e 100644
--- a/tests/test_rendertools.py
+++ b/tests/test_rendertools.py
@@ -36,7 +36,7 @@ def checkFrozenImage(sFileImage):
 
 def test_render_env():
     random.seed(100)
-    oEnv = RailEnv(width=10, height=10, rail_generator=random_rail_generator, number_of_agents=2)
+    oEnv = RailEnv(width=10, height=10, rail_generator=random_rail_generator(), number_of_agents=2)
     oEnv.reset()
     oRT = rt.RenderTool(oEnv)
     plt.figure(figsize=(10, 10))