diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index f04436d..c3105e2 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -2624,7 +2624,7 @@
     ngx_http_proxy_rewrite_t   *pr;
     ngx_http_script_compile_t   sc;
 
-    if (conf->upstream.store != 0) {
+    if (conf->upstream.store == NGX_CONF_UNSET) {
         ngx_conf_merge_value(conf->upstream.store,
                               prev->upstream.store, 0);