diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index 787b361..939e169 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -37,6 +37,7 @@
 #define NGX_HTTP_PROPPATCH                 0x0800
 #define NGX_HTTP_LOCK                      0x1000
 #define NGX_HTTP_UNLOCK                    0x2000
+#define NGX_HTTP_TRACE                     0x4000
 
 #define NGX_HTTP_CONNECTION_CLOSE          1
 #define NGX_HTTP_CONNECTION_KEEP_ALIVE     2