diff --git a/package-lock.json b/package-lock.json
index 83935455..7c0d9ae4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -31,7 +31,7 @@
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         "@types/node": "^18.19.39",
         "@types/sinon": "^17.0.3",
-        "chai": "^4.4.1",
+        "chai": "^5.1.1",
         "eslint": "^8.57.0",
         "eslint-config-teppeis": "^19.1.2",
         "mocha": "^10.5.2",
@@ -1247,13 +1247,13 @@
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+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-2.0.1.tgz",
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       "dev": true,
       "license": "MIT",
       "engines": {
-        "node": "*"
+        "node": ">=12"
       }
     },
     "node_modules/available-typed-arrays": {
@@ -1454,22 +1454,20 @@
       "license": "CC-BY-4.0"
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-      "resolved": "https://registry.npmjs.org/chai/-/chai-4.4.1.tgz",
-      "integrity": "sha512-13sOfMv2+DWduEU+/xbun3LScLoqN17nBeTLUsmDfKdoiC1fr0n9PU4guu4AhRcOVFk/sW8LyZWHuhWtQZiF+g==",
+      "version": "5.1.1",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-5.1.1.tgz",
+      "integrity": "sha512-pT1ZgP8rPNqUgieVaEY+ryQr6Q4HXNg8Ei9UnLUrjN4IA7dvQC5JB+/kxVcPNDHyBcc/26CXPkbNzq3qwrOEKA==",
       "dev": true,
       "license": "MIT",
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-        "assertion-error": "^1.1.0",
-        "check-error": "^1.0.3",
-        "deep-eql": "^4.1.3",
-        "get-func-name": "^2.0.2",
-        "loupe": "^2.3.6",
-        "pathval": "^1.1.1",
-        "type-detect": "^4.0.8"
+        "assertion-error": "^2.0.1",
+        "check-error": "^2.1.1",
+        "deep-eql": "^5.0.1",
+        "loupe": "^3.1.0",
+        "pathval": "^2.0.0"
       },
       "engines": {
-        "node": ">=4"
+        "node": ">=12"
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     "node_modules/chalk": {
@@ -1490,16 +1488,13 @@
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-      "resolved": "https://registry.npmjs.org/check-error/-/check-error-1.0.3.tgz",
-      "integrity": "sha512-iKEoDYaRmd1mxM90a2OEfWhjsjPpYPuQ+lMYsoxB126+t8fw7ySEO48nmDg5COTjxDI65/Y2OWpeEHk3ZOe8zg==",
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/check-error/-/check-error-2.1.1.tgz",
+      "integrity": "sha512-OAlb+T7V4Op9OwdkjmguYRqncdlx5JiofwOAUkmTF+jNdHwzTaTs4sRAGpzLF3oOz5xAyDGrPgeIDFQmDOTiJw==",
       "dev": true,
       "license": "MIT",
-      "dependencies": {
-        "get-func-name": "^2.0.2"
-      },
       "engines": {
-        "node": "*"
+        "node": ">= 16"
       }
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     "node_modules/chokidar": {
@@ -1813,14 +1808,11 @@
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-      "version": "4.1.4",
-      "resolved": "https://registry.npmjs.org/deep-eql/-/deep-eql-4.1.4.tgz",
-      "integrity": "sha512-SUwdGfqdKOwxCPeVYjwSyRpJ7Z+fhpwIAtmCUdZIWZ/YP5R9WAsyuSgpLVDi9bjWoN2LXHNss/dk3urXtdQxGg==",
+      "version": "5.0.2",
+      "resolved": "https://registry.npmjs.org/deep-eql/-/deep-eql-5.0.2.tgz",
+      "integrity": "sha512-h5k/5U50IJJFpzfL6nO9jaaumfjO/f2NjK/oYB2Djzm4p9L+3T9qWpZqZ2hAbLPuuYq9wrU08WQyBTL5GbPk5Q==",
       "dev": true,
       "license": "MIT",
-      "dependencies": {
-        "type-detect": "^4.0.0"
-      },
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         "node": ">=6"
       }
@@ -3990,9 +3982,9 @@
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-      "version": "2.3.7",
-      "resolved": "https://registry.npmjs.org/loupe/-/loupe-2.3.7.tgz",
-      "integrity": "sha512-zSMINGVYkdpYSOBmLi0D1Uo7JU9nVdQKrHxC8eYlV+9YKK9WePqAlL7lSlorG/U2Fw1w0hTBmaa/jrQ3UbPHtA==",
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/loupe/-/loupe-3.1.1.tgz",
+      "integrity": "sha512-edNu/8D5MKVfGVFRhFf8aAxiTM6Wumfz5XsaatSxlD3w4R1d/WEKUTydCdPGbl9K7QG/Ca3GnDV2sIKIpXRQcw==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -4768,13 +4760,13 @@
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-      "version": "1.1.1",
-      "resolved": "https://registry.npmjs.org/pathval/-/pathval-1.1.1.tgz",
-      "integrity": "sha512-Dp6zGqpTdETdR63lehJYPeIOqpiNBNtc7BpWSLrOje7UaIsE5aY92r/AunQA7rsXvet3lrJ3JnZX29UPTKXyKQ==",
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/pathval/-/pathval-2.0.0.tgz",
+      "integrity": "sha512-vE7JKRyES09KiunauX7nd2Q9/L7lhok4smP9RZTDeD4MVs72Dp2qNFVz39Nz5a0FVEW0BJR6C0DYrq6unoziZA==",
       "dev": true,
       "license": "MIT",
       "engines": {
-        "node": "*"
+        "node": ">= 14.16"
       }
     },
     "node_modules/picocolors": {
diff --git a/package.json b/package.json
index 03b8a914..d37a56df 100644
--- a/package.json
+++ b/package.json
@@ -47,7 +47,7 @@
     "@types/mocha": "^10.0.7",
     "@types/node": "^18.19.39",
     "@types/sinon": "^17.0.3",
-    "chai": "^4.4.1",
+    "chai": "^5.1.1",
     "eslint": "^8.57.0",
     "eslint-config-teppeis": "^19.1.2",
     "mocha": "^10.5.2",