diff --git a/src/lib/isCreditCard.js b/src/lib/isCreditCard.js
index 938679d39..706e3fb61 100644
--- a/src/lib/isCreditCard.js
+++ b/src/lib/isCreditCard.js
@@ -6,7 +6,7 @@ const cards = {
   dinersclub: /^3(?:0[0-5]|[68][0-9])[0-9]{11}$/,
   discover: /^6(?:011|5[0-9][0-9])[0-9]{12,15}$/,
   jcb: /^(?:2131|1800|35\d{3})\d{11}$/,
-  mastercard: /^5[1-5][0-9]{2}|(222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}$/, // /^[25][1-7][0-9]{14}$/;
+  mastercard: /^(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}$/, // /^[25][1-7][0-9]{14}$/;
   unionpay: /^(6[27][0-9]{14}|^(81[0-9]{14,17}))$/,
   visa: /^(?:4[0-9]{12})(?:[0-9]{3,6})?$/,
 };
diff --git a/test/validators.test.js b/test/validators.test.js
index a4c3d7193..a42648cf0 100644
--- a/test/validators.test.js
+++ b/test/validators.test.js
@@ -6387,7 +6387,7 @@ describe('Validators', () => {
       ],
       invalid: [
         'foo',
-        'foo',
+        '5108',
         '5398228707871528',
         '2718760626256571',
         '2721465526338453',
@@ -6570,6 +6570,7 @@ describe('Validators', () => {
       validator: 'isCreditCard',
       args: [{ provider: 'Mastercard' }],
       valid: [
+        '5105105105105100',
         '2222155765072228',
         '2225855203075256',
         '2718760626256570',
@@ -6578,6 +6579,8 @@ describe('Validators', () => {
       ],
       invalid: [
         'foo',
+        '5108',
+        '5108foo',
         '36050234196908',
         '375556917985515',
         '375556917985515999999993',