diff --git a/docs/libcurl/curl_url_cleanup.3 b/docs/libcurl/curl_url_cleanup.3
index f483d3a94e..2e32668e6d 100644
--- a/docs/libcurl/curl_url_cleanup.3
+++ b/docs/libcurl/curl_url_cleanup.3
@@ -32,6 +32,9 @@ void curl_url_cleanup(CURLU *handle);
 .fi
 .SH DESCRIPTION
 Frees all the resources associated with the given \fICURLU\fP handle!
+
+Passing in a NULL pointer in \fIhandle\fP will make this function return
+immediately with no action.
 .SH EXAMPLE
 .nf
   CURLU *url = curl_url();