diff --git a/package.json b/package.json
index 9fbf068..53d6a37 100644
--- a/package.json
+++ b/package.json
@@ -39,7 +39,7 @@
     "babel-preset-stage-2": "^6.22.0",
     "babel-register": "^6.22.0",
     "bootstrap": "^3.3.7",
-    "chai": "^3.5.0",
+    "chai": "^4.1.2",
     "chalk": "^1.1.3",
     "chromedriver": "^2.27.2",
     "connect-history-api-fallback": "^1.3.0",
diff --git a/yarn.lock b/yarn.lock
index 1d8594b..8a9f158 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1138,13 +1138,16 @@ chai-nightwatch@~0.1.x:
     assertion-error "1.0.0"
     deep-eql "0.1.3"
 
-chai@^3.5.0:
-  version "3.5.0"
-  resolved "https://registry.yarnpkg.com/chai/-/chai-3.5.0.tgz#4d02637b067fe958bdbfdd3a40ec56fef7373247"
+chai@^4.1.2:
+  version "4.1.2"
+  resolved "https://registry.yarnpkg.com/chai/-/chai-4.1.2.tgz#0f64584ba642f0f2ace2806279f4f06ca23ad73c"
   dependencies:
     assertion-error "^1.0.1"
-    deep-eql "^0.1.3"
-    type-detect "^1.0.0"
+    check-error "^1.0.1"
+    deep-eql "^3.0.0"
+    get-func-name "^2.0.0"
+    pathval "^1.0.0"
+    type-detect "^4.0.0"
 
 chalk@^1.0.0, chalk@^1.1.1, chalk@^1.1.3:
   version "1.1.3"
@@ -1164,6 +1167,10 @@ chalk@^2.1.0:
     escape-string-regexp "^1.0.5"
     supports-color "^4.0.0"
 
+check-error@^1.0.1:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/check-error/-/check-error-1.0.2.tgz#574d312edd88bb5dd8912e9286dd6c0aed4aac82"
+
 chokidar@^1.4.1, chokidar@^1.7.0:
   version "1.7.0"
   resolved "https://registry.yarnpkg.com/chokidar/-/chokidar-1.7.0.tgz#798e689778151c8076b4b360e5edd28cda2bb468"
@@ -1695,12 +1702,18 @@ decamelize@^1.0.0, decamelize@^1.1.1, decamelize@^1.1.2:
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/decamelize/-/decamelize-1.2.0.tgz#f6534d15148269b20352e7bee26f501f9a191290"
 
-deep-eql@0.1.3, deep-eql@^0.1.3:
+deep-eql@0.1.3:
   version "0.1.3"
   resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-0.1.3.tgz#ef558acab8de25206cd713906d74e56930eb69f2"
   dependencies:
     type-detect "0.1.1"
 
+deep-eql@^3.0.0:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-3.0.1.tgz#dfc9404400ad1c8fe023e7da1df1c147c4b444df"
+  dependencies:
+    type-detect "^4.0.0"
+
 deep-extend@~0.4.0:
   version "0.4.2"
   resolved "https://registry.yarnpkg.com/deep-extend/-/deep-extend-0.4.2.tgz#48b699c27e334bf89f10892be432f6e4c7d34a7f"
@@ -2561,6 +2574,10 @@ get-caller-file@^1.0.1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/get-caller-file/-/get-caller-file-1.0.2.tgz#f702e63127e7e231c160a80c1554acb70d5047e5"
 
+get-func-name@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/get-func-name/-/get-func-name-2.0.0.tgz#ead774abee72e20409433a066366023dd6887a41"
+
 get-stdin@^4.0.1:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/get-stdin/-/get-stdin-4.0.1.tgz#b968c6b0a04384324902e8bf1a5df32579a450fe"
@@ -4396,6 +4413,10 @@ path-type@^1.0.0:
     pify "^2.0.0"
     pinkie-promise "^2.0.0"
 
+pathval@^1.0.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/pathval/-/pathval-1.1.0.tgz#b942e6d4bde653005ef6b71361def8727d0645e0"
+
 pbkdf2@^3.0.3:
   version "3.0.13"
   resolved "https://registry.yarnpkg.com/pbkdf2/-/pbkdf2-3.0.13.tgz#c37d295531e786b1da3e3eadc840426accb0ae25"
@@ -5758,10 +5779,6 @@ type-detect@0.1.1:
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-0.1.1.tgz#0ba5ec2a885640e470ea4e8505971900dac58822"
 
-type-detect@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-1.0.0.tgz#762217cc06db258ec48908a1298e8b95121e8ea2"
-
 type-detect@^4.0.0:
   version "4.0.3"
   resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-4.0.3.tgz#0e3f2670b44099b0b46c284d136a7ef49c74c2ea"