--- a/src/http/modules/ngx_http_gzip_filter_module.c
+++ b/src/http/modules/ngx_http_gzip_filter_module.c
@@ -251,12 +251,22 @@ ngx_http_gzip_header_filter(ngx_http_req
             && r->headers_out.content_encoding->value.len)
         || (r->headers_out.content_length_n != -1
             && r->headers_out.content_length_n < conf->min_length)
-        || ngx_http_test_content_type(r, &conf->types) == NULL
-        || ngx_http_gzip_ok(r) != NGX_OK)
+        || ngx_http_test_content_type(r, &conf->types) == NULL)
     {
         return ngx_http_next_header_filter(r);
     }
 
+    r->gzip_vary = 1;
+
+    if (!r->gzip_tested) {
+        if (ngx_http_gzip_ok(r) != NGX_OK) {
+            return ngx_http_next_header_filter(r);
+        }
+
+    } else if (!r->gzip_ok) {
+        return ngx_http_next_header_filter(r);
+    }
+
     ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_gzip_ctx_t));
     if (ctx == NULL) {
         return NGX_ERROR;