diff --git a/src/http/ngx_http_parse.c b/src/http/ngx_http_parse.c
index 160f96dbe..d2abaa708 100644
--- a/src/http/ngx_http_parse.c
+++ b/src/http/ngx_http_parse.c
@@ -143,7 +143,7 @@ ngx_http_parse_request_line(ngx_http_request_t *r, ngx_buf_t *b)
                 break;
             }
 
-            if (ch < 'A' || ch > 'Z') {
+            if ((ch < 'A' || ch > 'Z') && ch != '_') {
                 return NGX_HTTP_PARSE_INVALID_METHOD;
             }
 
@@ -257,7 +257,7 @@ ngx_http_parse_request_line(ngx_http_request_t *r, ngx_buf_t *b)
                 break;
             }
 
-            if (ch < 'A' || ch > 'Z') {
+            if ((ch < 'A' || ch > 'Z') && ch != '_') {
                 return NGX_HTTP_PARSE_INVALID_METHOD;
             }