diff --git a/.eslintrc.json b/.eslintrc.json
index 414fb219..00516777 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -3,12 +3,10 @@
   "env": {
     "browser": true,
     "es6": true,
+    "es2020": true,
     "node": true
   },
   "parserOptions": {
     "ecmaVersion": "latest"
-  },
-  "globals": {
-    "BigInt": true
   }
 }
diff --git a/lib/client.js b/lib/client.js
index 1b3d5641..275abda9 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -2,7 +2,6 @@
 
 const { EventEmitter } = require('node:events');
 const WebSocket = require('ws');
-const { fetch } = require('metautil');
 const { MetaWritable, MetaReadable, chunkDecode } = require('./streams.js');
 
 const CALL_TIMEOUT = 7 * 1000;
diff --git a/package-lock.json b/package-lock.json
index bcc68af8..6e8e30d4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,7 @@
       "version": "3.1.2",
       "license": "MIT",
       "dependencies": {
-        "metautil": "^3.15.0",
+        "metautil": "4.0.1",
         "ws": "^8.14.0"
       },
       "devDependencies": {
@@ -21,7 +21,7 @@
         "eslint-plugin-import": "^2.28.1",
         "eslint-plugin-prettier": "^5.0.0",
         "metatests": "^0.8.2",
-        "prettier": "^3.0.3",
+        "prettier": "^3.1.0",
         "typescript": "^5.2.2"
       },
       "engines": {
@@ -57,18 +57,18 @@
       }
     },
     "node_modules/@eslint-community/regexpp": {
-      "version": "4.9.1",
-      "resolved": "https://registry.npmjs.org/@eslint-community/regexpp/-/regexpp-4.9.1.tgz",
-      "integrity": "sha512-Y27x+MBLjXa+0JWDhykM3+JE+il3kHKAEqabfEWq3SDhZjLYb6/BHL/JKFnH3fe207JaXkyDo685Oc2Glt6ifA==",
+      "version": "4.10.0",
+      "resolved": "https://registry.npmjs.org/@eslint-community/regexpp/-/regexpp-4.10.0.tgz",
+      "integrity": "sha512-Cu96Sd2By9mCNTx2iyKOmq10v22jUVQv0lQnlGNy16oE9589yE+QADPbrMGCkA51cKZSg3Pu/aTJVTGfL/qjUA==",
       "dev": true,
       "engines": {
         "node": "^12.0.0 || ^14.0.0 || >=16.0.0"
       }
     },
     "node_modules/@eslint/eslintrc": {
-      "version": "2.1.2",
-      "resolved": "https://registry.npmjs.org/@eslint/eslintrc/-/eslintrc-2.1.2.tgz",
-      "integrity": "sha512-+wvgpDsrB1YqAMdEUCcnTlpfVBH7Vqn6A/NT3D8WVXFIaKMlErPIZT3oCIAVCOtarRpMtelZLqJeU3t7WY6X6g==",
+      "version": "2.1.3",
+      "resolved": "https://registry.npmjs.org/@eslint/eslintrc/-/eslintrc-2.1.3.tgz",
+      "integrity": "sha512-yZzuIG+jnVu6hNSzFEN07e8BxF3uAzYtQb6uDkaYZLo6oYZDCq454c5kB8zxnzfCYyP4MIuyBn10L0DqwujTmA==",
       "dev": true,
       "dependencies": {
         "ajv": "^6.12.4",
@@ -89,9 +89,9 @@
       }
     },
     "node_modules/@eslint/js": {
-      "version": "8.52.0",
-      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-8.52.0.tgz",
-      "integrity": "sha512-mjZVbpaeMZludF2fsWLD0Z9gCref1Tk4i9+wddjRvpUNqqcndPkBD09N/Mapey0b3jaXbLm2kICwFv2E64QinA==",
+      "version": "8.54.0",
+      "resolved": "https://registry.npmjs.org/@eslint/js/-/js-8.54.0.tgz",
+      "integrity": "sha512-ut5V+D+fOoWPgGGNj83GGjnntO39xDy6DWxO0wb7Jp3DcMX0TfIqdzHF85VTQkerdyGmuuMD9AKAo5KiNlf/AQ==",
       "dev": true,
       "engines": {
         "node": "^12.22.0 || ^14.17.0 || >=16.0.0"
@@ -201,18 +201,18 @@
       "dev": true
     },
     "node_modules/@types/node": {
-      "version": "20.8.7",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.8.7.tgz",
-      "integrity": "sha512-21TKHHh3eUHIi2MloeptJWALuCu5H7HQTdTrWIFReA8ad+aggoX+lRes3ex7/FtpC+sVUpFMQ+QTfYr74mruiQ==",
+      "version": "20.9.2",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.9.2.tgz",
+      "integrity": "sha512-WHZXKFCEyIUJzAwh3NyyTHYSR35SevJ6mZ1nWwJafKtiQbqRTIKSRcw3Ma3acqgsent3RRDqeVwpHntMk+9irg==",
       "dev": true,
       "dependencies": {
-        "undici-types": "~5.25.1"
+        "undici-types": "~5.26.4"
       }
     },
     "node_modules/@types/ws": {
-      "version": "8.5.8",
-      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-8.5.8.tgz",
-      "integrity": "sha512-flUksGIQCnJd6sZ1l5dqCEG/ksaoAg/eUwiLAGTJQcfgvZJKF++Ta4bJA6A5aPSJmsr+xlseHn4KLgVlNnvPTg==",
+      "version": "8.5.9",
+      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-8.5.9.tgz",
+      "integrity": "sha512-jbdrY0a8lxfdTp/+r7Z4CkycbOFN8WX+IOchLJr3juT/xzbJ8URyTVSJ/hvNdadTgM1mnedb47n+Y31GsFnQlg==",
       "dev": true,
       "dependencies": {
         "@types/node": "*"
@@ -225,9 +225,9 @@
       "dev": true
     },
     "node_modules/acorn": {
-      "version": "8.10.0",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.10.0.tgz",
-      "integrity": "sha512-F0SAmZ8iUtS//m8DmCTA0jlh6TDKkHQyK6xc6V4KDTyZKA9dnvX9/3sRTVQrWm79glUAZbnmmNcdYwUIHWVybw==",
+      "version": "8.11.2",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.11.2.tgz",
+      "integrity": "sha512-nc0Axzp/0FILLEVsm4fNwLCwMttvhEI263QtVPQcbpfZZ3ts0hLsZGOpE6czNlid7CJ9MlyH8reXkpsf3YUY4w==",
       "dev": true,
       "bin": {
         "acorn": "bin/acorn"
@@ -823,15 +823,15 @@
       }
     },
     "node_modules/eslint": {
-      "version": "8.52.0",
-      "resolved": "https://registry.npmjs.org/eslint/-/eslint-8.52.0.tgz",
-      "integrity": "sha512-zh/JHnaixqHZsolRB/w9/02akBk9EPrOs9JwcTP2ek7yL5bVvXuRariiaAjjoJ5DvuwQ1WAE/HsMz+w17YgBCg==",
+      "version": "8.54.0",
+      "resolved": "https://registry.npmjs.org/eslint/-/eslint-8.54.0.tgz",
+      "integrity": "sha512-NY0DfAkM8BIZDVl6PgSa1ttZbx3xHgJzSNJKYcQglem6CppHyMhRIQkBVSSMaSRnLhig3jsDbEzOjwCVt4AmmA==",
       "dev": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.2.0",
         "@eslint-community/regexpp": "^4.6.1",
-        "@eslint/eslintrc": "^2.1.2",
-        "@eslint/js": "8.52.0",
+        "@eslint/eslintrc": "^2.1.3",
+        "@eslint/js": "8.54.0",
         "@humanwhocodes/config-array": "^0.11.13",
         "@humanwhocodes/module-importer": "^1.0.1",
         "@nodelib/fs.walk": "^1.2.8",
@@ -953,26 +953,26 @@
       }
     },
     "node_modules/eslint-plugin-import": {
-      "version": "2.28.1",
-      "resolved": "https://registry.npmjs.org/eslint-plugin-import/-/eslint-plugin-import-2.28.1.tgz",
-      "integrity": "sha512-9I9hFlITvOV55alzoKBI+K9q74kv0iKMeY6av5+umsNwayt59fz692daGyjR+oStBQgx6nwR9rXldDev3Clw+A==",
+      "version": "2.29.0",
+      "resolved": "https://registry.npmjs.org/eslint-plugin-import/-/eslint-plugin-import-2.29.0.tgz",
+      "integrity": "sha512-QPOO5NO6Odv5lpoTkddtutccQjysJuFxoPS7fAHO+9m9udNHvTCPSAMW9zGAYj8lAIdr40I8yPCdUYrncXtrwg==",
       "dev": true,
       "dependencies": {
-        "array-includes": "^3.1.6",
-        "array.prototype.findlastindex": "^1.2.2",
-        "array.prototype.flat": "^1.3.1",
-        "array.prototype.flatmap": "^1.3.1",
+        "array-includes": "^3.1.7",
+        "array.prototype.findlastindex": "^1.2.3",
+        "array.prototype.flat": "^1.3.2",
+        "array.prototype.flatmap": "^1.3.2",
         "debug": "^3.2.7",
         "doctrine": "^2.1.0",
-        "eslint-import-resolver-node": "^0.3.7",
+        "eslint-import-resolver-node": "^0.3.9",
         "eslint-module-utils": "^2.8.0",
-        "has": "^1.0.3",
-        "is-core-module": "^2.13.0",
+        "hasown": "^2.0.0",
+        "is-core-module": "^2.13.1",
         "is-glob": "^4.0.3",
         "minimatch": "^3.1.2",
-        "object.fromentries": "^2.0.6",
-        "object.groupby": "^1.0.0",
-        "object.values": "^1.1.6",
+        "object.fromentries": "^2.0.7",
+        "object.groupby": "^1.0.1",
+        "object.values": "^1.1.7",
         "semver": "^6.3.1",
         "tsconfig-paths": "^3.14.2"
       },
@@ -1162,9 +1162,9 @@
       "dev": true
     },
     "node_modules/fast-glob": {
-      "version": "3.3.1",
-      "resolved": "https://registry.npmjs.org/fast-glob/-/fast-glob-3.3.1.tgz",
-      "integrity": "sha512-kNFPyjhh5cKjrUltxs+wFx+ZkbRaxxmZ+X0ZU31SOsxCEtP9VPgtq2teZw1DebupL5GmDaNQ6yKMMVcM41iqDg==",
+      "version": "3.3.2",
+      "resolved": "https://registry.npmjs.org/fast-glob/-/fast-glob-3.3.2.tgz",
+      "integrity": "sha512-oX2ruAFQwf/Orj8m737Y5adxDQO0LAB7/S5MnxCdTNDd4p6BsyIVsv9JQsATbTSq8KHRpLwIHbVlUNatxd+1Ow==",
       "dev": true,
       "dependencies": {
         "@nodelib/fs.stat": "^2.0.2",
@@ -1251,9 +1251,9 @@
       }
     },
     "node_modules/flat-cache": {
-      "version": "3.1.1",
-      "resolved": "https://registry.npmjs.org/flat-cache/-/flat-cache-3.1.1.tgz",
-      "integrity": "sha512-/qM2b3LUIaIgviBQovTLvijfyOQXPtSRnRK26ksj2J7rzPIecePUIpJsZ4T02Qg+xiAEKIs5K8dsHEd+VaKa/Q==",
+      "version": "3.2.0",
+      "resolved": "https://registry.npmjs.org/flat-cache/-/flat-cache-3.2.0.tgz",
+      "integrity": "sha512-CYcENa+FtcUKLmhhqyctpclsq7QF38pKjZHsGNiSQF5r4FtoKDWabFDl3hzaEQMvT1LHEysw5twgLvpYYb4vbw==",
       "dev": true,
       "dependencies": {
         "flatted": "^3.2.9",
@@ -1261,7 +1261,7 @@
         "rimraf": "^3.0.2"
       },
       "engines": {
-        "node": ">=12.0.0"
+        "node": "^10.12.0 || >=12.0.0"
       }
     },
     "node_modules/flatted": {
@@ -1453,15 +1453,6 @@
       "integrity": "sha512-EtKwoO6kxCL9WO5xipiHTZlSzBm7WLT627TqC/uVRd0HKmq8NXyebnNYxDoBi7wt8eTWrUrKXCOVaFq9x1kgag==",
       "dev": true
     },
-    "node_modules/has": {
-      "version": "1.0.4",
-      "resolved": "https://registry.npmjs.org/has/-/has-1.0.4.tgz",
-      "integrity": "sha512-qdSAmqLF6209RFj4VVItywPMbm3vWylknmB3nvNiUIs72xAimcM8nVYxYr7ncvZq5qzk9MKIZR8ijqD/1QuYjQ==",
-      "dev": true,
-      "engines": {
-        "node": ">= 0.4.0"
-      }
-    },
     "node_modules/has-bigints": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/has-bigints/-/has-bigints-1.0.2.tgz",
@@ -1553,9 +1544,9 @@
       }
     },
     "node_modules/ignore": {
-      "version": "5.2.4",
-      "resolved": "https://registry.npmjs.org/ignore/-/ignore-5.2.4.tgz",
-      "integrity": "sha512-MAb38BcSbH0eHNBxn7ql2NH/kX33OkB3lZ1BNdh7ENeRChHTYsTvWrMubiIAMNS2llXEEgZ1MUOBtXChP3kaFQ==",
+      "version": "5.3.0",
+      "resolved": "https://registry.npmjs.org/ignore/-/ignore-5.3.0.tgz",
+      "integrity": "sha512-g7dmpshy+gD7mh88OC9NwSGTKoc3kyLAZQRU1mt53Aw/vnvfXnbC+F/7F7QoYVKbV+KNvJx8wArewKy1vXMtlg==",
       "dev": true,
       "engines": {
         "node": ">= 4"
@@ -2061,11 +2052,11 @@
       }
     },
     "node_modules/metautil": {
-      "version": "3.15.0",
-      "resolved": "https://registry.npmjs.org/metautil/-/metautil-3.15.0.tgz",
-      "integrity": "sha512-kGG920X8R10X6He2VKPRQFtG45DcDCSYgZehUFoqES52Tv88VALJm6EplZGwDRK7IiBDWsWDeS8d2OcW6bVXeg==",
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/metautil/-/metautil-4.0.1.tgz",
+      "integrity": "sha512-r12GixQz989n5T2JhWElNHF2CTg8df9ny4O4huPNEDBoVbMfQKivUemGfy2dmJaNV5OWrDgroyszjrhWyIU17g==",
       "engines": {
-        "node": "18 || 20"
+        "node": "18 || 20 || 21"
       },
       "funding": {
         "type": "patreon",
@@ -2422,9 +2413,9 @@
       }
     },
     "node_modules/prettier": {
-      "version": "3.0.3",
-      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.0.3.tgz",
-      "integrity": "sha512-L/4pUDMxcNa8R/EthV08Zt42WBO4h1rarVtK0K+QJG0X187OLo7l699jWw0GKuwzkPQ//jMFA/8Xm6Fh3J/DAg==",
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.1.0.tgz",
+      "integrity": "sha512-TQLvXjq5IAibjh8EpBIkNKxO749UEWABoiIZehEPiY4GNpVdhaFKqSTu+QrlU6D2dPAfubRmtJTi4K4YkQ5eXw==",
       "dev": true,
       "bin": {
         "prettier": "bin/prettier.cjs"
@@ -2449,9 +2440,9 @@
       }
     },
     "node_modules/punycode": {
-      "version": "2.3.0",
-      "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.0.tgz",
-      "integrity": "sha512-rRV+zQD8tVFys26lAGR9WUuS4iUAngJScM+ZRSKtvl5tKeZ2t5bvdNFdNHBW9FWR4guGHlgmsZ1G7BSm2wTbuA==",
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
+      "integrity": "sha512-vYt7UD1U9Wg6138shLtLOvdAu+8DsC/ilFtEVHcH+wydcSpNE20AfSOduf6MkRFahL5FY7X1oU7nKVZFtfq8Fg==",
       "dev": true,
       "engines": {
         "node": ">=6"
@@ -3171,9 +3162,9 @@
       }
     },
     "node_modules/undici-types": {
-      "version": "5.25.3",
-      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-5.25.3.tgz",
-      "integrity": "sha512-Ga1jfYwRn7+cP9v8auvEXN1rX3sWqlayd4HP7OKk4mZWylEmu3KzXDUGrQUN6Ol7qo1gPvB2e5gX6udnyEPgdA==",
+      "version": "5.26.5",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-5.26.5.tgz",
+      "integrity": "sha512-JlCMO+ehdEIKqlFxk6IfVoAUVmgz7cU7zD/h9XZ0qzeosSHmUJVOzSQvvYSYWXkFXC+IfLKSIffhv0sVZup6pA==",
       "dev": true
     },
     "node_modules/unicode-length": {
diff --git a/package.json b/package.json
index d51d2d84..531423b1 100644
--- a/package.json
+++ b/package.json
@@ -53,7 +53,7 @@
     "node": "18 || 20 || 21"
   },
   "dependencies": {
-    "metautil": "^3.15.0",
+    "metautil": "4.0.1",
     "ws": "^8.14.0"
   },
   "devDependencies": {
@@ -65,7 +65,7 @@
     "eslint-plugin-import": "^2.28.1",
     "eslint-plugin-prettier": "^5.0.0",
     "metatests": "^0.8.2",
-    "prettier": "^3.0.3",
+    "prettier": "^3.1.0",
     "typescript": "^5.2.2"
   }
 }
diff --git a/test/client.js b/test/client.js
index 28693127..6820edf6 100644
--- a/test/client.js
+++ b/test/client.js
@@ -29,7 +29,7 @@ metatests.test('Client / calls', async (test) => {
       },
       timeout: {
         handler: async () => {
-          await timers.setTimeout(200);
+          await timers.setTimeout(350);
           return { success: true };
         },
       },
@@ -64,7 +64,7 @@ metatests.test('Client / calls', async (test) => {
   test.defer(() => void mockServer.close());
 
   test.beforeEach(async () => {
-    client = Metacom.create('ws://localhost:8000/', { callTimeout: 150 });
+    client = Metacom.create('ws://localhost:8000/', { callTimeout: 300 });
     await client.opening;
     await client.load('test');
   });