diff --git a/src/index.js b/src/index.js
index 243d154..dd8c59e 100644
--- a/src/index.js
+++ b/src/index.js
@@ -5,7 +5,12 @@
  */
 
 const hammingDistance = (a, b) => {
-    
-  }
+    if(a.length != b.length)
+      throw new TypeError('Strings of different lengths');
+    const arrayA = a.split('');
+    const arrayB = b.split('');
+    return arrayA.reduce((acc, current, index) => (
+      current !== arrayB[index] ? ++acc : acc),0)
+}
   
   module.exports = hammingDistance;
\ No newline at end of file