diff --git a/package-lock.json b/package-lock.json
index e6276f2be5..e70ae36724 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -3821,9 +3821,9 @@
       }
     },
     "decamelize": {
-      "version": "4.0.0",
-      "resolved": "https://registry.npmjs.org/decamelize/-/decamelize-4.0.0.tgz",
-      "integrity": "sha512-9iE1PgSik9HeIIw2JO94IidnE3eBoQrFJ3w7sFuzSX4DpmZ3v5sZpUiV5Swcf6mQEF+Y0ru8Neo+p+nyh2J+hQ=="
+      "version": "5.0.0",
+      "resolved": "https://registry.npmjs.org/decamelize/-/decamelize-5.0.0.tgz",
+      "integrity": "sha512-U75DcT5hrio3KNtvdULAWnLiAPbFUC4191ldxMmj4FA/mRuBnmDwU0boNfPyFRhnan+Jm+haLeSn3P0afcBn4w=="
     },
     "decamelize-keys": {
       "version": "1.1.0",
@@ -11571,6 +11571,12 @@
         "is-plain-obj": "^2.1.0"
       },
       "dependencies": {
+        "decamelize": {
+          "version": "4.0.0",
+          "resolved": "https://registry.npmjs.org/decamelize/-/decamelize-4.0.0.tgz",
+          "integrity": "sha512-9iE1PgSik9HeIIw2JO94IidnE3eBoQrFJ3w7sFuzSX4DpmZ3v5sZpUiV5Swcf6mQEF+Y0ru8Neo+p+nyh2J+hQ==",
+          "dev": true
+        },
         "is-plain-obj": {
           "version": "2.1.0",
           "resolved": "https://registry.npmjs.org/is-plain-obj/-/is-plain-obj-2.1.0.tgz",
diff --git a/package.json b/package.json
index efad7b6d8d..78ef5afe5f 100644
--- a/package.json
+++ b/package.json
@@ -67,7 +67,7 @@
     "camelcase": "6.0.0",
     "chrome-launcher": "0.13.4",
     "debounce": "1.2.0",
-    "decamelize": "4.0.0",
+    "decamelize": "5.0.0",
     "es6-error": "4.1.1",
     "event-to-promise": "0.8.0",
     "firefox-profile": "4.0.0",
diff --git a/src/config.js b/src/config.js
index 8a4ec09347..c71585e431 100644
--- a/src/config.js
+++ b/src/config.js
@@ -54,7 +54,7 @@ export function applyConfigToArgv({
       continue;
     }
 
-    const decamelizedOptName = decamelize(option, '-');
+    const decamelizedOptName = decamelize(option, {separator: '-'});
 
     if (typeof options[decamelizedOptName] !== 'object') {
       throw new UsageError(`The config file at ${configFileName} specified ` +
diff --git a/src/program.js b/src/program.js
index 2de4d445d8..1787d70c92 100644
--- a/src/program.js
+++ b/src/program.js
@@ -214,7 +214,7 @@ export class Program {
     const cmd = yargsParser(this.programArgv)._[0];
     const env = systemProcess.env || {};
     const toOptionKey = (k) => decamelize(
-      camelCase(k.replace(envPrefix, '')), '-'
+      camelCase(k.replace(envPrefix, '')), {separator: '-'}
     );
 
     if (cmd) {