diff --git a/modules/http_client/TODO.txt b/modules/http_client/TODO.txt
index 81bde1b6073..3a23dd87311 100644
--- a/modules/http_client/TODO.txt
+++ b/modules/http_client/TODO.txt
@@ -89,6 +89,8 @@ Development API
   https://curl.haxx.se/libcurl/c/CURLOPT_CAINFO.html
   This can be set in the httpconf object
 
+- Document that some options like useragent doesn't work in the
+  old http_query function
 
 
 Issues in the bug tracker