diff --git a/docs/source/conf.py b/docs/source/conf.py
index 1f8a886e6..b9a908167 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -56,7 +56,7 @@ if os.getenv("READTHEDOCS"):
     else:
         release = yosys_ver
         todo_include_todos = False
-elif os.getenv("YOSYS_DOCS_RELEASE"):
+elif os.getenv("YOSYS_DOCS_RELEASE") is not None:
     release = yosys_ver
     todo_include_todos = False
 else: