diff --git a/nginx.conf b/nginx.conf
index 4a9f29d..00a5cb3 100644
--- a/nginx.conf
+++ b/nginx.conf
@@ -6,6 +6,9 @@
     include       /etc/nginx/mime.types;
     default_type  application/octet-stream;
 
+    # proxy_pass で変数を使う dev モード用（Docker 組み込み DNS）
+    resolver 127.0.0.11 valid=30s ipv6=off;
+
     map $http_upgrade $connection_upgrade {
         default upgrade;
         ''      close;