diff --git a/dist/angular-validation.js b/dist/angular-validation.js
index 3d6e780..6a6a5f3 100644
--- a/dist/angular-validation.js
+++ b/dist/angular-validation.js
@@ -688,7 +688,7 @@ angular.module('validation.directive', ['validation.provider']);
          * Set initial validity to undefined if no boolean value is transmitted
          */
         var initialValidity = void 0;
-        if (typeof attrs.initialValidity === 'boolean') {
+        if (typeof attrs.initialValidity === 'boolean' || attrs.initialValidity ==='true' || attrs.initialValidity ==='false') {
           initialValidity = attrs.initialValidity;
         }
 
@@ -697,6 +697,8 @@ angular.module('validation.directive', ['validation.provider']);
          */
         attrs.$observe('validator', function(value) {
           validation = value.split(',');
+          var theValue = useViewValue ? ctrl.$viewValue : ctrl.$modelValue;
+          checkValidation(scope, element, attrs, ctrl, validation, theValue);
         });
 
         /**
diff --git a/src/validator.directive.js b/src/validator.directive.js
index 9569d60..ba93522 100644
--- a/src/validator.directive.js
+++ b/src/validator.directive.js
@@ -310,7 +310,7 @@
          * Set initial validity to undefined if no boolean value is transmitted
          */
         var initialValidity = void 0;
-        if (typeof attrs.initialValidity === 'boolean') {
+        if (typeof attrs.initialValidity === 'boolean' || attrs.initialValidity ==='true' || attrs.initialValidity ==='false') {
           initialValidity = attrs.initialValidity;
         }
 
@@ -319,6 +319,9 @@
          */
         attrs.$observe('validator', function(value) {
           validation = value.split(',');
+          // validation has been updated => make rule fire again
+          var theValue = useViewValue ? ctrl.$viewValue : ctrl.$modelValue;
+          checkValidation(scope, element, attrs, ctrl, validation, theValue);
         });
 
         /**