diff --git a/Dockerfile b/Dockerfile
index 8082e84..66a9090 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.4
+# syntax=docker/dockerfile:1.25
 # aldabra — Cardano lite wallet over MCP.
 #
 # Multi-stage: