diff --git a/xml/en/docs/http/ngx_http_headers_module.xml b/xml/en/docs/http/ngx_http_headers_module.xml
index b4374c76..800faed8 100644
--- a/xml/en/docs/http/ngx_http_headers_module.xml
+++ b/xml/en/docs/http/ngx_http_headers_module.xml
@@ -72,6 +72,10 @@ If the always parameter is specified (1.7.5),
the header field will be added regardless of the response code.
+
+The add_header directive will not generate a header if the value provided is an empty string.
+
+