diff --git a/lib/cdist/__init__.py b/lib/cdist/__init__.py
index 864b4f37..1f325a8c 100644
--- a/lib/cdist/__init__.py
+++ b/lib/cdist/__init__.py
@@ -29,7 +29,7 @@ class Error(Exception):
 class MissingEnvironmentVariableError(Error):
     """Raised when a required environment variable is not set."""
 
-    def __init__(self, name)
+    def __init__(self, name):
         self.name = name
 
     def __str__(self):