diff --git a/index.js b/index.js
index 1e9648c..289fb19 100644
--- a/index.js
+++ b/index.js
@@ -1,2 +1,2 @@
 const leftPad = require('left-pad');
-module.exports = function pad5(s) { return leftPad(s, 5); };
+module.exports = function pad5(s) { return leftPad(String(s), 5); };
diff --git a/package-lock.json b/package-lock.json
index 25941fe..044f0a7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,9 +9,23 @@
       "version": "1.0.0",
       "license": "ISC",
       "dependencies": {
+        "inherits": "^2.0.4",
+        "isarray": "^2.0.5",
         "left-pad": "^1.3.0"
       }
     },
+    "node_modules/inherits": {
+      "version": "2.0.4",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
+      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
+      "license": "ISC"
+    },
+    "node_modules/isarray": {
+      "version": "2.0.5",
+      "resolved": "https://registry.npmjs.org/isarray/-/isarray-2.0.5.tgz",
+      "integrity": "sha512-xHjhDr3cNBK0BzdUJSPXZntQUx/mwMS5Rw4A7lPJ90XGAO6ISP/ePDNuo0vhqOZU+UD5JoodwCAAoZQd3FeAKw==",
+      "license": "MIT"
+    },
     "node_modules/left-pad": {
       "version": "1.3.0",
       "resolved": "https://registry.npmjs.org/left-pad/-/left-pad-1.3.0.tgz",
diff --git a/package.json b/package.json
index f6bdc7f..65f5640 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,8 @@
   "license": "ISC",
   "type": "commonjs",
   "dependencies": {
+    "inherits": "^2.0.4",
+    "isarray": "^2.0.5",
     "left-pad": "^1.3.0"
   }
 }
