diff --git a/index.js b/index.js
index 0ed4800..df7c1e7 100644
--- a/index.js
+++ b/index.js
@@ -41,7 +41,11 @@ module.exports = class Conf {
   merge (obj) {
     return _.mergeWith(this.config, obj, (configValue, overrideValue) => {
       // Do not apply merge on non-plain objects
-      if (typeof overrideValue === 'object' && overrideValue.constructor !== Object) {
+      if (
+        overrideValue &&
+        typeof overrideValue === 'object' &&
+        overrideValue.constructor !== Object
+      ) {
         return overrideValue
       }
 
diff --git a/test/unit/conf_tests.js b/test/unit/conf_tests.js
index 3da000a..0e02fb5 100644
--- a/test/unit/conf_tests.js
+++ b/test/unit/conf_tests.js
@@ -162,6 +162,13 @@ describe('The Conf', () => {
       expect(config.get('foo')).to.deep.equal(['quz'])
     })
 
+    it('merges null', function () {
+      const config = new Conf({foo: ['foo', 'bar']})
+
+      config.merge({foo: null})
+      expect(config.config.foo).to.deep.equal(null)
+    })
+
     it('does not merge class instances, keeps the original object', function () {
       class Foo {
         constructor () {