diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 780528a33..d5e6dd5e6 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -569,8 +569,11 @@ ngx_http_upstream_connect(ngx_http_request_t *r, ngx_http_upstream_t *u)
         }
     }
 
-    if (r->request_body && r->request_body->temp_file && r == r->main) {
-
+    if (r->request_body
+        && r->request_body->buf
+        && r->request_body->temp_file
+        && r == r->main)
+    {
         /*
          * the r->request_body->buf can be reused for one request only,
          * the subrequests should allocate their own temporay bufs