diff --git a/functions/info.xml b/functions/info.xml
index 54a307d44f..6d14373e2d 100644
--- a/functions/info.xml
+++ b/functions/info.xml
@@ -1258,7 +1258,9 @@ if (substr(php_uname(), 0, 7) == "Windows") {
      </funcprototype>
     </funcsynopsis>
     <para>
-     Adds <parameter>setting</parameter> to the server environment.
+     Adds <parameter>setting</parameter> to the server environment.  The
+environment variable will only exist for the duration of the current request.
+At the end of the request the environment is restored to its original state.
     </para>
     <para>
      <example>