diff --git a/addon/format.js b/addon/format.js
index b51d973..d4eadb9 100755
--- a/addon/format.js
+++ b/addon/format.js
@@ -13,6 +13,7 @@ const {
   isEmpty,
   assert,
   deprecate,
+  canInvoke,
   getProperties
 } = Ember;
 
@@ -68,7 +69,7 @@ export default function validateFormat(value, options, model, attribute) {
     set(options, 'regex', regex);
   }
 
-  if (regex && !regex.test(value)) {
+  if (!canInvoke(value, 'match') || (regex && isEmpty(value.match(regex)))) {
     return validationError(type || 'invalid', value, options);
   }
 
diff --git a/tests/unit/validators/format-test.js b/tests/unit/validators/format-test.js
index c98bdcc..0f951e5 100644
--- a/tests/unit/validators/format-test.js
+++ b/tests/unit/validators/format-test.js
@@ -60,6 +60,9 @@ test('email', function(assert) {
     'EMAIL@DOMAIN.COM'
   ];
   let invalidAddresses = [
+    null,
+    undefined,
+    404,
     'plainaddress',
     '#@%^%#$@#$@#.com',
     '@domain.com',
@@ -170,7 +173,7 @@ test('url', function(assert) {
 });
 
 test('custom', function(assert) {
-  assert.expect(2);
+  assert.expect(3);
 
   options = {
     regex: /^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{4,8}$/
@@ -178,9 +181,31 @@ test('custom', function(assert) {
 
   options = cloneOptions(options);
 
+  result = validate(null, options);
+  assert.equal(processResult(result), 'This field is invalid');
+
   result = validate('password', options);
   assert.equal(processResult(result), 'This field is invalid');
 
   result = validate('Pass123', options);
   assert.equal(processResult(result), true);
 });
+
+test('custom with g flag', function(assert) {
+  assert.expect(3);
+
+  options = {
+    regex: /foo/g
+  };
+
+  options = cloneOptions(options);
+
+  result = validate('foo', options);
+  assert.equal(processResult(result), true);
+
+  result = validate('foo', options);
+  assert.equal(processResult(result), true);
+
+  result = validate('bar', options);
+  assert.equal(processResult(result), 'This field is invalid');
+});