diff --git a/package-lock.json b/package-lock.json
index 4ede3c8..1f17827 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -457,9 +457,9 @@
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@@ -693,12 +693,9 @@
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-      "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
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-      "requires": {
-        "sprintf-js": "~1.0.2"
-      }
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+      "resolved": "https://registry.npmjs.org/argparse/-/argparse-2.0.1.tgz",
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@@ -1545,6 +1542,15 @@
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+          "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
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+          "dev": true,
+          "requires": {
+            "sprintf-js": "~1.0.2"
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           "resolved": "https://registry.npmjs.org/import-fresh/-/import-fresh-2.0.0.tgz",
@@ -1555,6 +1561,16 @@
             "resolve-from": "^3.0.0"
           }
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+        "js-yaml": {
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+          "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.14.1.tgz",
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+          "dev": true,
+          "requires": {
+            "argparse": "^1.0.7",
+            "esprima": "^4.0.0"
+          }
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           "resolved": "https://registry.npmjs.org/resolve-from/-/resolve-from-3.0.0.tgz",
@@ -2000,6 +2016,15 @@
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+        "argparse": {
+          "version": "1.0.10",
+          "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
+          "integrity": "sha512-o5Roy6tNG4SL/FOkCAN6RzjiakZS25RLYFrcMttJqbdd8BWrnA+fGz57iN5Pb06pvBGvl5gQ0B48dJlslXvoTg==",
+          "dev": true,
+          "requires": {
+            "sprintf-js": "~1.0.2"
+          }
+        },
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           "resolved": "https://registry.npmjs.org/cross-spawn/-/cross-spawn-6.0.5.tgz",
@@ -2027,6 +2052,16 @@
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           "dev": true
         },
+        "js-yaml": {
+          "version": "3.14.1",
+          "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.14.1.tgz",
+          "integrity": "sha512-okMH7OXXJ7YrN9Ok3/SXrnu4iX9yOk+25nqX4imS2npuvTYDmo/QEZoqwZkYaIDk3jVvBOTOIEgEhaLOynBS9g==",
+          "dev": true,
+          "requires": {
+            "argparse": "^1.0.7",
+            "esprima": "^4.0.0"
+          }
+        },
         "strip-json-comments": {
           "version": "3.0.1",
           "resolved": "https://registry.npmjs.org/strip-json-comments/-/strip-json-comments-3.0.1.tgz",
@@ -2433,7 +2468,8 @@
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-      "integrity": "sha512-eGuFFw7Upda+g4p+QHvnW0RyTX/SVeJBDM/gCtMARO0cLuT2HcEKnTPvhjV6aGeqrCB/sbNop0Kszm0jsaWU4A=="
+      "integrity": "sha512-eGuFFw7Upda+g4p+QHvnW0RyTX/SVeJBDM/gCtMARO0cLuT2HcEKnTPvhjV6aGeqrCB/sbNop0Kszm0jsaWU4A==",
+      "dev": true
     },
     "espurify": {
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@@ -2813,6 +2849,27 @@
         "extend-shallow": "^2.0.1",
         "js-yaml": "^3.8.1",
         "toml": "^2.3.2"
+      },
+      "dependencies": {
+        "argparse": {
+          "version": "1.0.10",
+          "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
+          "integrity": "sha512-o5Roy6tNG4SL/FOkCAN6RzjiakZS25RLYFrcMttJqbdd8BWrnA+fGz57iN5Pb06pvBGvl5gQ0B48dJlslXvoTg==",
+          "dev": true,
+          "requires": {
+            "sprintf-js": "~1.0.2"
+          }
+        },
+        "js-yaml": {
+          "version": "3.14.1",
+          "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.14.1.tgz",
+          "integrity": "sha512-okMH7OXXJ7YrN9Ok3/SXrnu4iX9yOk+25nqX4imS2npuvTYDmo/QEZoqwZkYaIDk3jVvBOTOIEgEhaLOynBS9g==",
+          "dev": true,
+          "requires": {
+            "argparse": "^1.0.7",
+            "esprima": "^4.0.0"
+          }
+        }
       }
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     "has": {
@@ -3497,12 +3554,11 @@
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-      "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.13.1.tgz",
-      "integrity": "sha512-YfbcO7jXDdyj0DGxYVSlSeQNHbD7XPWvrVWeVUujrQEoZzWJIRrCPoyk6kL6IAjAG2IolMK4T0hNUe0HOUs5Jw==",
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-4.0.0.tgz",
+      "integrity": "sha512-pqon0s+4ScYUvX30wxQi3PogGFAlUyH0awepWvwkj4jD4v+ova3RiYw8bmA6x2rDrEaj8i/oWKoRxpVNW+Re8Q==",
       "requires": {
-        "argparse": "^1.0.7",
-        "esprima": "^4.0.0"
+        "argparse": "^2.0.1"
       }
     },
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@@ -5532,7 +5588,8 @@
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       "resolved": "https://registry.npmjs.org/sprintf-js/-/sprintf-js-1.0.3.tgz",
-      "integrity": "sha1-BOaSb2YolTVPPdAVIDYzuFcpfiw="
+      "integrity": "sha1-BOaSb2YolTVPPdAVIDYzuFcpfiw=",
+      "dev": true
     },
     "stack-utils": {
       "version": "1.0.2",
@@ -5688,6 +5745,15 @@
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           "dev": true
         },
+        "argparse": {
+          "version": "1.0.10",
+          "resolved": "https://registry.npmjs.org/argparse/-/argparse-1.0.10.tgz",
+          "integrity": "sha512-o5Roy6tNG4SL/FOkCAN6RzjiakZS25RLYFrcMttJqbdd8BWrnA+fGz57iN5Pb06pvBGvl5gQ0B48dJlslXvoTg==",
+          "dev": true,
+          "requires": {
+            "sprintf-js": "~1.0.2"
+          }
+        },
         "arrify": {
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           "resolved": "https://registry.npmjs.org/arrify/-/arrify-1.0.1.tgz",
@@ -5700,6 +5766,16 @@
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           "dev": true
         },
+        "js-yaml": {
+          "version": "3.14.1",
+          "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-3.14.1.tgz",
+          "integrity": "sha512-okMH7OXXJ7YrN9Ok3/SXrnu4iX9yOk+25nqX4imS2npuvTYDmo/QEZoqwZkYaIDk3jVvBOTOIEgEhaLOynBS9g==",
+          "dev": true,
+          "requires": {
+            "argparse": "^1.0.7",
+            "esprima": "^4.0.0"
+          }
+        },
         "strip-ansi": {
           "version": "4.0.0",
           "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-4.0.0.tgz",
diff --git a/package.json b/package.json
index 6d351e5..1a75535 100644
--- a/package.json
+++ b/package.json
@@ -84,14 +84,14 @@
     "@types/metalsmith": "2.3.0",
     "debug": "4.1.1",
     "deep-freeze-strict": "1.1.1",
-    "js-yaml": "3.13.1",
+    "js-yaml": "4.0.0",
     "multimatch": "4.0.0"
   },
   "devDependencies": {
     "@sounisi5011/check-peer-deps": "github:sounisi5011/check-peer-deps",
     "@types/debug": "4.1.5",
     "@types/deep-freeze-strict": "1.1.0",
-    "@types/js-yaml": "3.12.1",
+    "@types/js-yaml": "4.0.0",
     "@types/lodash.clonedeep": "4.5.6",
     "@types/node": "*",
     "@typescript-eslint/eslint-plugin": "2.2.0",