diff --git a/src/jquery.maskedinput.js b/src/jquery.maskedinput.js
index 749da65..287596d 100644
--- a/src/jquery.maskedinput.js
+++ b/src/jquery.maskedinput.js
@@ -19,7 +19,8 @@ $.mask = {
 		'*': "[A-Za-z0-9]"
 	},
 	dataName: "rawMaskFn",
-	placeholder: '_'
+	placeholder: '_',
+	transform: function(string){return string;}
 };
 
 $.fn.extend({
@@ -73,6 +74,7 @@ $.fn.extend({
 		}
 		settings = $.extend({
 			placeholder: $.mask.placeholder, // Load default placeholder
+			transform: $.mask.transform,
 			completed: null
 		}, settings);
 
@@ -205,7 +207,7 @@ $.fn.extend({
 
 					p = seekNext(pos.begin - 1);
 					if (p < len) {
-						c = String.fromCharCode(k);
+						c = settings.transform(String.fromCharCode(k));
 						if (tests[p].test(c)) {
 							shiftR(p);