diff --git a/server_environment/README.rst b/server_environment/README.rst
index a230714..ef1c2b3 100644
--- a/server_environment/README.rst
+++ b/server_environment/README.rst
@@ -68,6 +68,8 @@ used values are 'dev', 'test', 'production'::
 Values associated to keys containing 'passw' are only displayed in the 'dev'
 environment.
 
+If you don't provide any value, `test` is used as a safe default.
+
 You have several possibilities to set configuration values:
 
 server_environment_files
diff --git a/server_environment/static/description/index.html b/server_environment/static/description/index.html
index 0157657..67d8ba8 100644
--- a/server_environment/static/description/index.html
+++ b/server_environment/static/description/index.html
@@ -424,6 +424,7 @@ running_env=dev
 </pre>
 <p>Values associated to keys containing ‘passw’ are only displayed in the ‘dev’
 environment.</p>
+<p>If you don’t provide any value, <cite>test</cite> is used as a safe default.</p>
 <p>You have several possibilities to set configuration values:</p>
 <div class="section" id="server-environment-files">
 <h2><a class="toc-backref" href="#id3">server_environment_files</a></h2>