diff --git a/src/utils/core.js b/src/utils/core.js
index 1e8af8a..31ff2bd 100644
--- a/src/utils/core.js
+++ b/src/utils/core.js
@@ -93,16 +93,16 @@ export function isFloat(n) {
 export function prefixed(unprefixed) {
 	var vendors = ["Webkit", "webkit", "Moz", "O", "ms" ];
 	var prefixes = ["-webkit-", "-webkit-", "-moz-", "-o-", "-ms-"];
-	var upper = unprefixed[0].toUpperCase() + unprefixed.slice(1);
+	var lower = unprefixed.toLowerCase();
 	var length = vendors.length;
 
-	if (typeof(document) === "undefined" || typeof(document.body.style[unprefixed]) != "undefined") {
+	if (typeof(document) === "undefined" || typeof(document.body.style[lower]) != "undefined") {
 		return unprefixed;
 	}
 
-	for ( var i=0; i < length; i++ ) {
-		if (typeof(document.body.style[vendors[i] + upper]) != "undefined") {
-			return prefixes[i] + unprefixed;
+	for (var i = 0; i < length; i++) {
+		if (typeof(document.body.style[prefixes[i] + lower]) != "undefined") {
+			return prefixes[i] + lower;
 		}
 	}