diff --git a/package-lock.json b/package-lock.json
index 48d1f52..e6d417a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,7 +13,7 @@
         "@askalf/strongroom": "git+https://github.com/askalf/strongroom.git#9718edcae54b9bdee9f725cc4d5edae4abc2bbf8",
         "@askalf/truecopy": "git+https://github.com/askalf/truecopy.git#55582d9b89dfdb9bbe6eea8face7ecc85ac21e24",
         "@modelcontextprotocol/sdk": "^1.29.0",
-        "zod": "^3.25.0"
+        "zod": "^4.4.3"
       },
       "bin": {
         "oys-mcp": "bin/oys-mcp.mjs"
@@ -1216,9 +1216,9 @@
       "license": "ISC"
     },
     "node_modules/zod": {
-      "version": "3.25.76",
-      "resolved": "https://registry.npmjs.org/zod/-/zod-3.25.76.tgz",
-      "integrity": "sha512-gzUt/qt81nXsFGKIFcC3YnfEAx5NkunCfnDlvuBSSFS02bcXu4Lmea0AFIUwbLWxWPx3d9p8S5QoaujKcNQxcQ==",
+      "version": "4.4.3",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-4.4.3.tgz",
+      "integrity": "sha512-ytENFjIJFl2UwYglde2jchW2Hwm4GJFLDiSXWdTrJQBIN9Fcyp7n4DhxJEiWNAJMV1/BqWfW/kkg71UDcHJyTQ==",
       "license": "MIT",
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
diff --git a/package.json b/package.json
index 8d02087..a4baba8 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,7 @@
     "@askalf/truecopy": "git+https://github.com/askalf/truecopy.git#55582d9b89dfdb9bbe6eea8face7ecc85ac21e24",
     "@askalf/strongroom": "git+https://github.com/askalf/strongroom.git#9718edcae54b9bdee9f725cc4d5edae4abc2bbf8",
     "@modelcontextprotocol/sdk": "^1.29.0",
-    "zod": "^3.25.0"
+    "zod": "^4.4.3"
   },
   "keywords": [
     "ai-agents",