diff --git a/lib/angular-payments.js b/lib/angular-payments.js
index 9e7bb49..fb2a94d 100755
--- a/lib/angular-payments.js
+++ b/lib/angular-payments.js
@@ -617,7 +617,14 @@ angular.module('angularPayments', []);angular.module('angularPayments')
           typeModel.assign(scope, card.type);
       }
 
-      ret = (ref = num.length, __indexOf.call(card.length, ref) >= 0) && (card.luhn === false || _luhnCheck(num));
+      var length = 16;
+      switch (card.type) {
+        case 'amex':
+          length = 15;
+          break;
+      }
+
+      ret = (ref = num.length, __indexOf.call(card.length, ref) >= 0) && num.length == length && (card.luhn === false || _luhnCheck(num));
 
       return ret;
   }
diff --git a/src/validate.js b/src/validate.js
index ecf412c..2b4242b 100644
--- a/src/validate.js
+++ b/src/validate.js
@@ -98,7 +98,14 @@ angular.module('angularPayments')
           typeModel.assign(scope, card.type);
       }
 
-      ret = (ref = num.length, __indexOf.call(card.length, ref) >= 0) && (card.luhn === false || _luhnCheck(num));
+      var length = 16;
+      switch (card.type) {
+        case 'amex':
+          length = 15;
+          break;
+      }
+
+      ret = (ref = num.length, __indexOf.call(card.length, ref) >= 0) && num.length == length && (card.luhn === false || _luhnCheck(num));
 
       return ret;
   }