diff --git a/src/http/ngx_http_special_response.c b/src/http/ngx_http_special_response.c
index 76e670588..72f56fd9a 100644
--- a/src/http/ngx_http_special_response.c
+++ b/src/http/ngx_http_special_response.c
@@ -575,6 +575,10 @@ ngx_http_clean_header(ngx_http_request_t *r)
     r->headers_out.headers.part.next = NULL;
     r->headers_out.headers.last = &r->headers_out.headers.part;
 
+    r->headers_out.trailers.part.nelts = 0;
+    r->headers_out.trailers.part.next = NULL;
+    r->headers_out.trailers.last = &r->headers_out.trailers.part;
+
     r->headers_out.content_length_n = -1;
     r->headers_out.last_modified_time = -1;
 }