diff --git a/wagtail_modeltranslation/static/wagtail_modeltranslation/js/wagtail_translated_slugs.js b/wagtail_modeltranslation/static/wagtail_modeltranslation/js/wagtail_translated_slugs.js
index 5b60bd1..80c8e1a 100644
--- a/wagtail_modeltranslation/static/wagtail_modeltranslation/js/wagtail_translated_slugs.js
+++ b/wagtail_modeltranslation/static/wagtail_modeltranslation/js/wagtail_translated_slugs.js
@@ -8,13 +8,13 @@ $(document).ready(function () {
             $('#id_title_' + lang_code).on('focus', function () {
                 /* slug should only follow the title field if its value matched the title's value at the time of focus */
                 var currentSlug = $('#id_slug_' + lang_code).val();
-                var slugifiedTitle = cleanForSlug(this.value);
+                var slugifiedTitle = cleanForSlug(this.value, true);
                 slugFollowsTitle = (currentSlug == slugifiedTitle);
             });
 
             $('#id_title_' + lang_code).on('keyup keydown keypress blur', function () {
                 if (slugFollowsTitle) {
-                    var slugifiedTitle = cleanForSlug(this.value);
+                    var slugifiedTitle = cleanForSlug(this.value, true);
                     $('#id_slug_' + lang_code).val(slugifiedTitle);
                 }
             });