diff --git a/lib/ipv4.js b/lib/ipv4.js
index 3da9cfe7..477aa574 100644
--- a/lib/ipv4.js
+++ b/lib/ipv4.js
@@ -317,4 +317,15 @@ Address4.prototype.binaryZeroPad = function () {
   return padStart(this.bigInteger().toString(2), constants.BITS, '0');
 };
 
+/**
+ * Returns the ip representation of subnet mask
+ * @memberof Address4
+ * @instance
+ * @returns {string} subnetMaskIP
+ */
+Address4.prototype.subnetMaskIP = function () {
+  const shiftBits = constants.BITS - this.subnetMask;
+  return Address4.fromInteger(((0xffffffff << shiftBits) & 0xffffffff) >>> 0).correctForm()
+};
+
 module.exports = Address4;
diff --git a/package.json b/package.json
index 082a286f..cc62df93 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
     "browser",
     "validation"
   ],
-  "version": "6.2.0",
+  "version": "6.2.1",
   "author": "Beau Gunderson <beau@beaugunderson.com> (https://beaugunderson.com/)",
   "license": "MIT",
   "main": "ip-address.js",
diff --git a/test/functionality-v4-test.js b/test/functionality-v4-test.js
index e560b793..7a740c73 100644
--- a/test/functionality-v4-test.js
+++ b/test/functionality-v4-test.js
@@ -259,4 +259,12 @@ describe('v4', function () {
       });
     });
   });
+
+  describe('An IP with CIDR notation', function () {
+    var topic = new Address4('127.0.0.2/20');
+
+    it('should generate IP representation of subnet mask correctly', function () {
+      topic.subnetMaskIP().should.equal('255.255.240.0');
+    });
+  });
 });