diff --git a/polyfill.js b/polyfill.js
new file mode 100644
index 0000000..bce9725
--- /dev/null
+++ b/polyfill.js
@@ -0,0 +1,19 @@
+if (!String.prototype.padStart) {
+  String.prototype.padStart = function padStart(targetLength, padString) {
+    targetLength = targetLength >> 0; //floor if number or convert non-number to 0;
+    padString = String(typeof padString !== 'undefined' ? padString : ' ');
+    if (this.length > targetLength) {
+      return String(this);
+    } else {
+      targetLength = targetLength - this.length;
+      if (targetLength > padString.length) {
+        padString += padString.repeat(targetLength / padString.length); //append to original to ensure we are longer than needed
+      }
+      return padString.slice(0, targetLength) + String(this);
+    }
+  }
+}
+
+Number.prototype.toHex = function () {
+	return this.toString(16).padStart(2, "0")
+}
diff --git a/util.js b/util.js
new file mode 100644
index 0000000..e69de29