diff --git a/src/nouislider.js b/src/nouislider.js
index b5b4011a..93ee741d 100644
--- a/src/nouislider.js
+++ b/src/nouislider.js
@@ -108,7 +108,7 @@
 
     // http://youmightnotneedjquery.com/#remove_class
     function removeClass(el, className) {
-        if (el.classList) {
+        if (el.classList && !/\s/.test(className)) {
             el.classList.remove(className);
         } else {
             el.className = el.className.replace(