diff --git a/sigal/__init__.py b/sigal/__init__.py
index c866c12..6e59f51 100644
--- a/sigal/__init__.py
+++ b/sigal/__init__.py
@@ -40,7 +40,7 @@ try:
     __version__ = get_distribution(__name__).version
 except DistributionNotFound:
     # package is not installed
-    pass
+    __version__ = None
 
 __url__ = 'https://github.com/saimn/sigal'