diff --git a/package-lock.json b/package-lock.json
index fcd07164..e7bb4406 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1323,6 +1323,7 @@
       "resolved": "https://registry.npmjs.org/boom/-/boom-0.4.2.tgz",
       "integrity": "sha1-emNune1O/O+xnO9JR6PGffrukRs=",
       "dev": true,
+      "optional": true,
       "requires": {
         "hoek": "0.9.x"
       }
@@ -1524,14 +1525,17 @@
       "dev": true
     },
     "chai": {
-      "version": "3.5.0",
-      "resolved": "https://registry.npmjs.org/chai/-/chai-3.5.0.tgz",
-      "integrity": "sha1-TQJjewZ/6Vi9v906QOxW/vc3Mkc=",
+      "version": "4.2.0",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-4.2.0.tgz",
+      "integrity": "sha512-XQU3bhBukrOsQCuwZndwGcCVQHyZi53fQ6Ys1Fym7E4olpIqqZZhhoFJoaKVvV17lWQoXYwgWN2nF5crA8J2jw==",
       "dev": true,
       "requires": {
-        "assertion-error": "^1.0.1",
-        "deep-eql": "^0.1.3",
-        "type-detect": "^1.0.0"
+        "assertion-error": "^1.1.0",
+        "check-error": "^1.0.2",
+        "deep-eql": "^3.0.1",
+        "get-func-name": "^2.0.0",
+        "pathval": "^1.1.0",
+        "type-detect": "^4.0.5"
       }
     },
     "chalk": {
@@ -1546,6 +1550,12 @@
         "supports-color": "^2.0.0"
       }
     },
+    "check-error": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/check-error/-/check-error-1.0.2.tgz",
+      "integrity": "sha1-V00xLt2Iu13YkS6Sht1sCu1KrII=",
+      "dev": true
+    },
     "chokidar": {
       "version": "1.7.0",
       "resolved": "https://registry.npmjs.org/chokidar/-/chokidar-1.7.0.tgz",
@@ -1960,20 +1970,12 @@
       "integrity": "sha1-JJXduvbrh0q7Dhvp3yLS5aVEMmw="
     },
     "deep-eql": {
-      "version": "0.1.3",
-      "resolved": "https://registry.npmjs.org/deep-eql/-/deep-eql-0.1.3.tgz",
-      "integrity": "sha1-71WKyrjeJSBs1xOQbXTlaTDrafI=",
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/deep-eql/-/deep-eql-3.0.1.tgz",
+      "integrity": "sha512-+QeIQyN5ZuO+3Uk5DYh6/1eKO0m0YmJFGNmFHGACpf1ClL1nmlV/p4gNgbl2pJGxgXb4faqo6UE+M5ACEMyVcw==",
       "dev": true,
       "requires": {
-        "type-detect": "0.1.1"
-      },
-      "dependencies": {
-        "type-detect": {
-          "version": "0.1.1",
-          "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-0.1.1.tgz",
-          "integrity": "sha1-C6XsKohWQORw6k6FBZcZANrFiCI=",
-          "dev": true
-        }
+        "type-detect": "^4.0.0"
       }
     },
     "deep-equal": {
@@ -2849,6 +2851,7 @@
           "version": "0.0.9",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "inherits": "~2.0.0"
           }
@@ -2873,7 +2876,8 @@
         "buffer-shims": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "caseless": {
           "version": "0.12.0",
@@ -2890,12 +2894,14 @@
         "code-point-at": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "combined-stream": {
           "version": "1.0.5",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "delayed-stream": "~1.0.0"
           }
@@ -2908,17 +2914,20 @@
         "console-control-strings": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "core-util-is": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "cryptiles": {
           "version": "2.0.5",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "boom": "2.x.x"
           }
@@ -2958,7 +2967,8 @@
         "delayed-stream": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "delegates": {
           "version": "1.0.0",
@@ -2990,7 +3000,8 @@
         "extsprintf": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "forever-agent": {
           "version": "0.6.1",
@@ -3113,6 +3124,7 @@
           "version": "3.1.3",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "boom": "2.x.x",
             "cryptiles": "2.x.x",
@@ -3160,6 +3172,7 @@
           "version": "1.0.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -3173,7 +3186,8 @@
         "isarray": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "isstream": {
           "version": "0.1.2",
@@ -3246,12 +3260,14 @@
         "mime-db": {
           "version": "1.27.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "mime-types": {
           "version": "2.1.15",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "mime-db": "~1.27.0"
           }
@@ -3327,7 +3343,8 @@
         "number-is-nan": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "oauth-sign": {
           "version": "0.8.2",
@@ -3385,7 +3402,8 @@
         "process-nextick-args": {
           "version": "1.0.7",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "punycode": {
           "version": "1.4.1",
@@ -3423,6 +3441,7 @@
           "version": "2.2.9",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "buffer-shims": "~1.0.0",
             "core-util-is": "~1.0.0",
@@ -3474,7 +3493,8 @@
         "safe-buffer": {
           "version": "5.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "semver": {
           "version": "5.3.0",
@@ -3498,6 +3518,7 @@
           "version": "1.0.9",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "hoek": "2.x.x"
           }
@@ -3531,6 +3552,7 @@
           "version": "1.0.2",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -3541,6 +3563,7 @@
           "version": "1.0.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "safe-buffer": "^5.0.1"
           }
@@ -3569,6 +3592,7 @@
           "version": "2.2.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "block-stream": "*",
             "fstream": "^1.0.2",
@@ -3624,7 +3648,8 @@
         "util-deprecate": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "uuid": {
           "version": "3.0.1",
@@ -3688,6 +3713,12 @@
         "is-property": "^1.0.0"
       }
     },
+    "get-func-name": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/get-func-name/-/get-func-name-2.0.0.tgz",
+      "integrity": "sha1-6td0q+5y4gQJQzoGY2YCPdaIekE=",
+      "dev": true
+    },
     "get-stdin": {
       "version": "4.0.1",
       "resolved": "https://registry.npmjs.org/get-stdin/-/get-stdin-4.0.1.tgz",
@@ -5875,6 +5906,7 @@
           "version": "0.1.4",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "kind-of": "^3.0.2",
             "longest": "^1.0.1",
@@ -6624,7 +6656,8 @@
         "longest": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "loose-envify": {
           "version": "1.3.1",
@@ -7516,6 +7549,12 @@
         "pinkie-promise": "^2.0.0"
       }
     },
+    "pathval": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/pathval/-/pathval-1.1.0.tgz",
+      "integrity": "sha1-uULm1L3mUwBe9rcTYd74cn0GReA=",
+      "dev": true
+    },
     "pause-stream": {
       "version": "0.0.11",
       "resolved": "https://registry.npmjs.org/pause-stream/-/pause-stream-0.0.11.tgz",
@@ -9234,9 +9273,9 @@
       }
     },
     "type-detect": {
-      "version": "1.0.0",
-      "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-1.0.0.tgz",
-      "integrity": "sha1-diIXzAbbJY7EiQihKY6LlRIejqI=",
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-4.0.8.tgz",
+      "integrity": "sha512-0fr/mIH1dlO+x7TlcMy+bIDqKPsw/70tVyeHW787goQjhmqaZe10uwLujubK9q9Lg6Fiho1KUKDYz0Z7k7g5/g==",
       "dev": true
     },
     "typedarray": {
diff --git a/package.json b/package.json
index 67f91346..e7e68347 100644
--- a/package.json
+++ b/package.json
@@ -53,7 +53,7 @@
     "babel-core": "6.26.3",
     "babel-preset-es2015": "6.24.1",
     "babel-preset-stage-2": "6.24.1",
-    "chai": "3.5.0",
+    "chai": "4.2.0",
     "codecov.io": "0.1.6",
     "cz-conventional-changelog-default-export": "0.0.0-semantically-released.1",
     "eslint": "3.19.0",