diff --git a/src/js/uppercaseOnly-directive.js b/src/js/uppercaseOnly-directive.js
index c4bca73..d73427f 100644
--- a/src/js/uppercaseOnly-directive.js
+++ b/src/js/uppercaseOnly-directive.js
@@ -25,7 +25,9 @@ angular.module('focaDirectivas')
                         return value.toUpperCase();
                     }
 
-                    if(attrs.type === 'text') {
+                    if(attrs.type === 'text' &&
+                        !attrs.readonly &&
+                        !attrs.disabled) {
     
                         ctrl.$formatters.push(formatter);
                         ctrl.$parsers.push(parser);