diff --git a/package.json b/package.json
index 54838c4..b3fe2a2 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
     "babel-plugin-transform-es2015-modules-umd": "^6.24.1",
     "babel-preset-stage-0": "^6.24.1",
     "babel-watch": "^2.0.7",
-    "chai": "^4.2.0",
+    "chai": "^4.3.3",
     "jest": "^23.5.0",
     "jest-cucumber": "^1.0.11"
   }
diff --git a/yarn.lock b/yarn.lock
index 1442845..b4b0885 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -938,7 +938,7 @@ assertion-error-formatter@^2.0.1:
     pad-right "^0.2.2"
     repeat-string "^1.6.1"
 
-assertion-error@^1.0.1, assertion-error@^1.1.0:
+assertion-error@^1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/assertion-error/-/assertion-error-1.1.0.tgz#e60b6b0e8f301bd97e5375215bda406c85118c0b"
 
@@ -1468,7 +1468,7 @@ becke-ch--regex--s0-0-v1--base--pl--lib@^1.2.0:
 
 bignumber.js@^2.1.0:
   version "2.4.0"
-  resolved "http://registry.npmjs.org/bignumber.js/-/bignumber.js-2.4.0.tgz#838a992da9f9d737e0f4b2db0be62bb09dd0c5e8"
+  resolved "https://registry.npmjs.org/bignumber.js/-/bignumber.js-2.4.0.tgz#838a992da9f9d737e0f4b2db0be62bb09dd0c5e8"
 
 binary-extensions@^1.0.0:
   version "1.11.0"
@@ -1738,26 +1738,16 @@ center-align@^0.1.1:
     align-text "^0.1.3"
     lazy-cache "^1.0.3"
 
-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"
-    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"
-
-chai@^4.2.0:
-  version "4.2.0"
-  resolved "https://registry.yarnpkg.com/chai/-/chai-4.2.0.tgz#760aa72cf20e3795e84b12877ce0e83737aa29e5"
+chai@^4.1.2, chai@^4.3.3:
+  version "4.3.3"
+  resolved "https://registry.yarnpkg.com/chai/-/chai-4.3.3.tgz#f2b2ad9736999d07a7ff95cf1e7086c43a76f72d"
+  integrity sha512-MPSLOZwxxnA0DhLE84klnGPojWFK5KuhP7/j5dTsxpr2S3XlkqJP5WbyYl1gCTWvG2Z5N+HD4F472WsbEZL6Pw==
   dependencies:
     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"
+    pathval "^1.1.1"
     type-detect "^4.0.5"
 
 chalk@^1.1.3:
@@ -1787,7 +1777,7 @@ chalk@^2.4.1:
     escape-string-regexp "^1.0.5"
     supports-color "^5.3.0"
 
-check-error@^1.0.1, check-error@^1.0.2:
+check-error@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/check-error/-/check-error-1.0.2.tgz#574d312edd88bb5dd8912e9286dd6c0aed4aac82"
 
@@ -2198,7 +2188,7 @@ decode-uri-component@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/decode-uri-component/-/decode-uri-component-0.2.0.tgz#eb3913333458775cb84cd1a1fae062106bb87545"
 
-deep-eql@^3.0.0, deep-eql@^3.0.1:
+deep-eql@^3.0.1:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-3.0.1.tgz#dfc9404400ad1c8fe023e7da1df1c147c4b444df"
   dependencies:
@@ -2418,7 +2408,7 @@ es6-iterator@~2.0.3:
 
 es6-promise@^3.0.2:
   version "3.3.1"
-  resolved "http://registry.npmjs.org/es6-promise/-/es6-promise-3.3.1.tgz#a08cdde84ccdbf34d027a1451bc91d4bcd28a613"
+  resolved "https://registry.npmjs.org/es6-promise/-/es6-promise-3.3.1.tgz#a08cdde84ccdbf34d027a1451bc91d4bcd28a613"
 
 es6-symbol@^3.1.1, es6-symbol@~3.1.1:
   version "3.1.1"
@@ -2624,7 +2614,7 @@ figures@2.0.0:
 
 file-type@^3.1.0:
   version "3.9.0"
-  resolved "http://registry.npmjs.org/file-type/-/file-type-3.9.0.tgz#257a078384d1db8087bc449d107d52a52672b9e9"
+  resolved "https://registry.npmjs.org/file-type/-/file-type-3.9.0.tgz#257a078384d1db8087bc449d107d52a52672b9e9"
 
 filename-regex@^2.0.0:
   version "2.0.1"
@@ -4358,7 +4348,7 @@ minimist@^1.1.0, minimist@^1.1.1, minimist@^1.2.0:
 
 minimist@~0.0.1:
   version "0.0.10"
-  resolved "http://registry.npmjs.org/minimist/-/minimist-0.0.10.tgz#de3f98543dbf96082be48ad1a0c7cda836301dcf"
+  resolved "https://registry.npmjs.org/minimist/-/minimist-0.0.10.tgz#de3f98543dbf96082be48ad1a0c7cda836301dcf"
 
 minipass@^2.2.1, minipass@^2.3.3:
   version "2.3.3"
@@ -4814,9 +4804,10 @@ path-type@^3.0.0:
   dependencies:
     pify "^3.0.0"
 
-pathval@^1.0.0, pathval@^1.1.0:
-  version "1.1.0"
-  resolved "https://registry.yarnpkg.com/pathval/-/pathval-1.1.0.tgz#b942e6d4bde653005ef6b71361def8727d0645e0"
+pathval@^1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/pathval/-/pathval-1.1.1.tgz#8534e77a77ce7ac5a2512ea21e0fdb8fcf6c3d8d"
+  integrity sha512-Dp6zGqpTdETdR63lehJYPeIOqpiNBNtc7BpWSLrOje7UaIsE5aY92r/AunQA7rsXvet3lrJ3JnZX29UPTKXyKQ==
 
 pbkdf2@^3.0.3:
   version "3.0.16"
@@ -6120,7 +6111,7 @@ wordwrap@~1.0.0:
 
 wrap-ansi@^2.0.0:
   version "2.1.0"
-  resolved "http://registry.npmjs.org/wrap-ansi/-/wrap-ansi-2.1.0.tgz#d8fc3d284dd05794fe84973caecdd1cf824fdd85"
+  resolved "https://registry.npmjs.org/wrap-ansi/-/wrap-ansi-2.1.0.tgz#d8fc3d284dd05794fe84973caecdd1cf824fdd85"
   dependencies:
     string-width "^1.0.1"
     strip-ansi "^3.0.1"