diff --git a/tests/unittests/model/test_quota_co2_yaml.py b/tests/unittests/model/test_quota_co2_yaml.py
index ffbb15ff..e414dc2b 100644
--- a/tests/unittests/model/test_quota_co2_yaml.py
+++ b/tests/unittests/model/test_quota_co2_yaml.py
@@ -26,7 +26,7 @@
 """
 build the quota CO² test system.
 
-    N1 -----N2----Demand         ^
+    N1 -----N2----Demand
     |       |
     Oil1    Coal1
     |       |