diff --git a/src/http/ngx_http_variables.c b/src/http/ngx_http_variables.c
index c3e1f60..5aac76b 100644
--- a/src/http/ngx_http_variables.c
+++ b/src/http/ngx_http_variables.c
@@ -1304,6 +1304,7 @@
         if (ngx_strncmp(v[i].name.data, "upstream_http_", 14) == 0) {
             v[i].get_handler = ngx_http_upstream_header_variable;
             v[i].data = (uintptr_t) &v[i].name;
+            v[i].flags = NGX_HTTP_VAR_NOCACHABLE;
 
             continue;
         }