diff --git a/exercises/trinary/trinary.py b/exercises/trinary/trinary.py
index cb410441109..eaac98ef4e8 100644
--- a/exercises/trinary/trinary.py
+++ b/exercises/trinary/trinary.py
@@ -1,2 +1,2 @@
-def trinary():
+def trinary(string):
     pass