diff --git a/src/http/ngx_http.h b/src/http/ngx_http.h
index 8c07a90..cac2a9c 100644
--- a/src/http/ngx_http.h
+++ b/src/http/ngx_http.h
@@ -76,6 +76,9 @@
     ngx_uint_t allow_underscores);
 ngx_int_t ngx_http_parse_multi_header_lines(ngx_array_t *headers,
     ngx_str_t *name, ngx_str_t *value);
+ngx_int_t ngx_http_arg(ngx_http_request_t *r, u_char *name, size_t len,
+    ngx_str_t *value);
+
 
 ngx_int_t ngx_http_find_server_conf(ngx_http_request_t *r);
 void ngx_http_update_location_config(ngx_http_request_t *r);