diff --git a/README.md b/README.md
index 672a325..2f18dde 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ Finds degree of similarity between two strings, based on [Dice's Coefficient](ht
 * [Release Notes](#release-notes)
     * [2.0.0](#200)
     * [3.0.0](#300)
+    * [3.0.1](#301)
 
 
 ## Usage
@@ -119,6 +120,9 @@ stringSimilarity.findBestMatch('Olive-green table for sale, in extremely good co
 * The algorithm has been tweaked slightly to disregard spaces and word boundaries. This will change the rating values slightly but not enough to make a significant difference
 * Adding a `bestMatchIndex` to the results for `findBestMatch(..)` to point to the best match in the supplied `targetStrings` array
 
+### 3.0.1
+* Refactoring: removed unused functions; used `substring` instead of `substr`
+* Updated dependencies
 
 ![Build status](https://codeship.com/projects/2aa453d0-0959-0134-8a76-4abcb29fe9b4/status?branch=master)
 [![Known Vulnerabilities](https://snyk.io/test/github/aceakash/string-similarity/badge.svg)](https://snyk.io/test/github/aceakash/string-similarity)
diff --git a/compare-strings.js b/compare-strings.js
index 9cb5c44..094d8c2 100644
--- a/compare-strings.js
+++ b/compare-strings.js
@@ -15,7 +15,7 @@ function compareTwoStrings(first, second) {
 
 	let firstBigrams = new Map();
 	for (let i = 0; i < first.length - 1; i++) {
-		const bigram = first.substr(i, 2);
+		const bigram = first.substring(i, i + 2);
 		const count = firstBigrams.has(bigram)
 			? firstBigrams.get(bigram) + 1
 			: 1;
@@ -25,7 +25,7 @@ function compareTwoStrings(first, second) {
 
 	let intersectionSize = 0;
 	for (let i = 0; i < second.length - 1; i++) {
-		const bigram = second.substr(i, 2);
+		const bigram = second.substring(i, i + 2);
 		const count = firstBigrams.has(bigram)
 			? firstBigrams.get(bigram)
 			: 0;
@@ -60,10 +60,6 @@ function findBestMatch(mainString, targetStrings) {
 	return { ratings, bestMatch, bestMatchIndex };
 }
 
-function flattenDeep(arr) {
-	return Array.isArray(arr) ? arr.reduce((a, b) => a.concat(flattenDeep(b)), []) : [arr];
-}
-
 function areArgsValid(mainString, targetStrings) {
 	if (typeof mainString !== 'string') return false;
 	if (!Array.isArray(targetStrings)) return false;
@@ -71,14 +67,3 @@ function areArgsValid(mainString, targetStrings) {
 	if (targetStrings.find(s => typeof s !== 'string')) return false;
 	return true;
 }
-
-function letterPairs(str) {
-	const pairs = [];
-	for (let i = 0, max = str.length - 1; i < max; i++) pairs[i] = str.substring(i, i + 2);
-	return pairs;
-}
-
-function wordLetterPairs(str) {
-	const pairs = str.toUpperCase().split(' ').map(letterPairs);
-	return flattenDeep(pairs);
-}
diff --git a/package-lock.json b/package-lock.json
index 51a12b4..9dab287 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "string-similarity",
-  "version": "3.0.0",
+  "version": "3.0.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
@@ -63,19 +63,19 @@
       "dev": true
     },
     "jasmine": {
-      "version": "3.3.1",
-      "resolved": "https://registry.npmjs.org/jasmine/-/jasmine-3.3.1.tgz",
-      "integrity": "sha512-/vU3/H7U56XsxIXHwgEuWpCgQ0bRi2iiZeUpx7Nqo8n1TpoDHfZhkPIc7CO8I4pnMzYsi3XaSZEiy8cnTfujng==",
+      "version": "3.4.0",
+      "resolved": "https://registry.npmjs.org/jasmine/-/jasmine-3.4.0.tgz",
+      "integrity": "sha512-sR9b4n+fnBFDEd7VS2el2DeHgKcPiMVn44rtKFumq9q7P/t8WrxsVIZPob4UDdgcDNCwyDqwxCt4k9TDRmjPoQ==",
       "dev": true,
       "requires": {
-        "glob": "^7.0.6",
-        "jasmine-core": "~3.3.0"
+        "glob": "^7.1.3",
+        "jasmine-core": "~3.4.0"
       }
     },
     "jasmine-core": {
-      "version": "3.3.0",
-      "resolved": "https://registry.npmjs.org/jasmine-core/-/jasmine-core-3.3.0.tgz",
-      "integrity": "sha512-3/xSmG/d35hf80BEN66Y6g9Ca5l/Isdeg/j6zvbTYlTzeKinzmaTM4p9am5kYqOmE05D7s1t8FGjzdSnbUbceA==",
+      "version": "3.4.0",
+      "resolved": "https://registry.npmjs.org/jasmine-core/-/jasmine-core-3.4.0.tgz",
+      "integrity": "sha512-HU/YxV4i6GcmiH4duATwAbJQMlE0MsDIR5XmSVxURxKHn3aGAdbY1/ZJFmVRbKtnLwIxxMJD7gYaPsypcbYimg==",
       "dev": true
     },
     "minimatch": {
diff --git a/package.json b/package.json
index ceffcd5..1ab353d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "string-similarity",
-  "version": "3.0.0",
+  "version": "3.0.1",
   "description": "Finds degree of similarity between strings, based on Dice's Coefficient, which is mostly better than Levenshtein distance.",
   "main": "compare-strings.js",
   "scripts": {
@@ -29,6 +29,6 @@
   "author": "Akash Kurdekar <npm@kurdekar.com> (http://untilfalse.com/)",
   "license": "ISC",
   "devDependencies": {
-    "jasmine": "^3.3.0"
+    "jasmine": "^3.4.0"
   }
 }