diff --git a/README.md b/README.md
index 31e1270..195ca54 100644
--- a/README.md
+++ b/README.md
@@ -50,7 +50,8 @@ The **req.files.foo** object will contain the following:
 
 * Before 1.0.0, `md5` is an MD5 checksum of the uploaded file.
 * From 1.0.0 until 1.1.1, `md5` is a function to compute an MD5 hash ([Read about it here.](https://github.com/richardgirges/express-fileupload/releases/tag/v1.0.0-alpha.1)).
-* From 1.1.1 onward, `md5` is reverted back to MD5 checksum value and also added full MD5 support in case you are using temporary files.
+* From 1.1.1 until 1.5.1, `md5` is reverted back to MD5 checksum value and also added full MD5 support in case you are using temporary files.
+* From 1.5.1 onward, `md5` still holds the checksum value, but the checksum is generated with the provided `hashAlgorithm` option. The property name remains `md5` for backwards compatibility.
 
 
 ### Examples
@@ -124,6 +125,7 @@ parseNested | <ul><li><code>false</code>&nbsp;**(default)**</li><li><code>true</
 debug | <ul><li><code>false</code>&nbsp;**(default)**</li><li><code>true</code></ul> | Turn on/off upload process logging. Can be useful for troubleshooting.
 logger | <ul><li><code>console</code>&nbsp;**(default)**</li><li><code>{log: function(msg: string)}</code></li></ul> | Customizable logger to write debug messages to. Console is default.
 uploadTimeout | <ul><li><code>60000</code>&nbsp;**(default)**</li><li><code>Integer</code></ul> | This defines how long to wait for data before aborting. Set to 0 if you want to turn off timeout checks.
+hashAlgorithm | <ul><li><code>md5</code>&nbsp;**(default)**</li><li><code>String</code></li></ul> | Allows the usage of alternative hashing algorithms for file integrity checks. This option must be an algorithm that is supported on the running system's installed OpenSSL version. On recent releases of OpenSSL, <code>openssl list -digest-algorithms</code> will display the available digest algorithms.
 
 # Help Wanted
 Looking for additional maintainers. Please contact `richardgirges [ at ] gmail.com` if you're interested. Pull Requests are welcome! 
diff --git a/lib/utilities.js b/lib/utilities.js
index 2cbf583..1545399 100644
--- a/lib/utilities.js
+++ b/lib/utilities.js
@@ -69,6 +69,7 @@ const promiseCallback = (resolve, reject) => {
 /**
  * Builds instance options from arguments objects(can't be arrow function).
  * @returns {Object} - result options.
+ * @throws {Error} - when a valid hashAlgorithm option is not provided.
  */
 const buildOptions = function() {
   const result = {};
@@ -77,16 +78,11 @@ const buildOptions = function() {
     Object.keys(options).forEach(i => result[i] = options[i]);
   });
 
-  // Ensure a hashAlgorithm option exists.
-  if (!result.hashAlgorithm) {
-    result.hashAlgorithm = 'md5';
-  }
-
   // Ensure the configured hashAlgorithm is available on the system
   if (crypto.getHashes().find(h => result.hashAlgorithm === h) === undefined) {
     throw Error(
-      `Hashing algorithm '${result.hashAlgorithm}' is not supported by this system's OpenSSL ` +
-      `version`
+      `Hashing algorithm '${result.hashAlgorithm}' is not supported by this system's OpenSSL `
+      + `version`
     );
   }
 
diff --git a/package.json b/package.json
index a5f2785..6360fbe 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "express-fileupload",
-  "version": "1.5.0",
+  "version": "1.5.1",
   "author": "Richard Girges <richardgirges@gmail.com>",
   "description": "Simple express file upload middleware that wraps around Busboy",
   "main": "./lib/index",
diff --git a/test/utilities.spec.js b/test/utilities.spec.js
index 90380e0..1386df5 100644
--- a/test/utilities.spec.js
+++ b/test/utilities.spec.js
@@ -198,19 +198,15 @@ describe('utilities: Test of the utilities functions', function() {
   //buildOptions tests
   describe('Test buildOptions function', () => {
 
-    const source = { option1: '1', option2: '2' };
+    const source = { option1: '1', option2: '2', hashAlgorithm: 'md5' };
     const sourceAddon = { option3: '3', hashAlgorithm: 'sha256'};
     const expected = { option1: '1', option2: '2', hashAlgorithm: 'md5' };
     const expectedAddon = { option1: '1', option2: '2', option3: '3', hashAlgorithm: 'sha256'};
 
-    it(
-      'buildOptions returns an equal object to the object which was passed + hashAlgorithm '
-      + 'property',
-      () => {
-        let result = buildOptions(source);
-        assert.deepStrictEqual(result, expected);
-      }
-    );
+    it('buildOptions returns an equal object to the object which was passed', () => {
+      let result = buildOptions(source);
+      assert.deepStrictEqual(result, source);
+    });
 
     it('buildOptions doesnt add non object or null arguments to the result', () => {
       let result = buildOptions(source, 2, '3', null);
@@ -222,6 +218,10 @@ describe('utilities: Test of the utilities functions', function() {
       assert.deepStrictEqual(result, expectedAddon);
     });
 
+    it('buildOptions throws an error when not provided a supported hashAlgorithm', () => {
+      assert.throws(() => buildOptions({}));
+    });
+
     it('buildOptions throws an error when given an unsupported hashAlgorithm', () => {
       assert.throws(() => buildOptions({ hashAlgorithm: 'not-actual-algo' }));
     });