diff --git a/package-lock.json b/package-lock.json
index 0a4fd900..66cb9b94 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -36,7 +36,7 @@
         "eslint-config-teppeis": "^19.1.2",
         "mocha": "^10.8.2",
         "npm-run-all": "^4.1.5",
-        "prettier": "^3.4.2",
+        "prettier": "^3.8.2",
         "rimraf": "^5.0.10",
         "sinon": "^17.0.2",
         "tempy": "^3.1.0",
@@ -622,7 +622,6 @@
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       "dev": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "undici-types": "~5.26.4"
       }
@@ -691,7 +690,6 @@
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       "dev": true,
       "license": "BSD-2-Clause",
-      "peer": true,
       "dependencies": {
         "@typescript-eslint/scope-manager": "7.18.0",
         "@typescript-eslint/types": "7.18.0",
@@ -927,7 +925,6 @@
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.14.0.tgz",
       "integrity": "sha512-cl669nCJTZBsL97OF4kUQm5g5hC2uihk0NxY3WENAC0TYdILVkAyHymAntgxGkl7K+t0cXIrH5siy5S4XkFycA==",
       "license": "MIT",
-      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -1279,7 +1276,6 @@
         }
       ],
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "caniuse-lite": "^1.0.30001688",
         "electron-to-chromium": "^1.5.73",
@@ -2184,7 +2180,6 @@
       "deprecated": "This version is no longer supported. Please see https://eslint.org/version-support for other options.",
       "dev": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.2.0",
         "@eslint-community/regexpp": "^4.6.1",
@@ -2426,7 +2421,6 @@
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       "dev": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "@rtsao/scc": "^1.1.0",
         "array-includes": "^3.1.8",
@@ -2729,7 +2723,6 @@
       "resolved": "https://registry.npmjs.org/estraverse/-/estraverse-5.3.0.tgz",
       "integrity": "sha512-MMdARuVEQziNTeJD8DgMqmhwR11BRQ/cBP+pLtYdSTnf3MIO8fFeiINEbX36ZdNlfU/7A9f3gUw49B3oQsvwBA==",
       "license": "BSD-2-Clause",
-      "peer": true,
       "engines": {
         "node": ">=4.0"
       }
@@ -5050,12 +5043,11 @@
       }
     },
     "node_modules/prettier": {
-      "version": "3.4.2",
-      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.4.2.tgz",
-      "integrity": "sha512-e9MewbtFo+Fevyuxn/4rrcDAaq0IYxPGLvObpQjiZBMAzB9IGmzlnG9RZy3FFas+eBMu2vA0CszMeduow5dIuQ==",
+      "version": "3.8.2",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-3.8.2.tgz",
+      "integrity": "sha512-8c3mgTe0ASwWAJK+78dpviD+A8EqhndQPUBpNUIPt6+xWlIigCwfN01lWr9MAede4uqXGTEKeQWTvzb3vjia0Q==",
       "dev": true,
       "license": "MIT",
-      "peer": true,
       "bin": {
         "prettier": "bin/prettier.cjs"
       },
@@ -6429,7 +6421,6 @@
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       "dev": true,
       "license": "Apache-2.0",
-      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
diff --git a/package.json b/package.json
index b2d418ca..c026a151 100644
--- a/package.json
+++ b/package.json
@@ -52,7 +52,7 @@
     "eslint-config-teppeis": "^19.1.2",
     "mocha": "^10.8.2",
     "npm-run-all": "^4.1.5",
-    "prettier": "^3.4.2",
+    "prettier": "^3.8.2",
     "rimraf": "^5.0.10",
     "sinon": "^17.0.2",
     "tempy": "^3.1.0",