diff --git a/doc/en/fixture.rst b/doc/en/fixture.rst
index be071302a..a9352a19f 100644
--- a/doc/en/fixture.rst
+++ b/doc/en/fixture.rst
@@ -326,7 +326,7 @@ containers for different environments. See the example below.
 .. code-block:: python
 
     def determine_scope(fixture_name, config):
-        if config.getoption("--keep-containers"):
+        if config.getoption("--keep-containers", None):
             return "session"
         return "function"