diff --git a/inginious/frontend/static/js/task_dispensers.js b/inginious/frontend/static/js/task_dispensers.js
index a0b3a6a54..96ae99b64 100644
--- a/inginious/frontend/static/js/task_dispensers.js
+++ b/inginious/frontend/static/js/task_dispensers.js
@@ -138,10 +138,8 @@ function dispenser_util_add_tasks_to_section(button) {
             // Copy and add the new fields
             var new_modal_clone = $("#edit-modals-template").clone();
             new_modal_clone.html(new_modal_clone.html().replaceAll("NEWTASKID", selected_tasks[i]));
-            new_modal_clone.find(".categories").selectize({delimiter: ",", persist: false,
-                create: function (input) { return {value: input, text: input}; },
-            });
             $("#edit-modals").append(new_modal_clone.children(".modal"));
+            $("#edit-modals").trigger("new_task");
             dispenser_add_task(selected_tasks[i]);
         }
     }
diff --git a/inginious/frontend/templates/course_admin/task_dispensers/config_items/categories.html b/inginious/frontend/templates/course_admin/task_dispensers/config_items/categories.html
index d78a72286..b9f20bbe5 100644
--- a/inginious/frontend/templates/course_admin/task_dispensers/config_items/categories.html
+++ b/inginious/frontend/templates/course_admin/task_dispensers/config_items/categories.html
@@ -30,6 +30,19 @@
             $("#edit_" + $(this).data("taskid") +  " input.categories").val(value).change();
         });
     });
+
+    $(function() {
+        $("#edit-modals .categories").each(function () {
+            $(this).selectize({delimiter: ",", persist: false,
+                create: function (input) { return { value: input, text: input }; }
+            });
+        });
+        $("#edit-modals").on("new_task", function () {
+            $(this).find(".categories").last().selectize({delimiter: ",", persist: false,
+                create: function (input) { return { value: input, text: input }; }
+            });
+        });
+    });
 </script>
 {% endif %}
 {% endif %}
diff --git a/inginious/frontend/templates/course_admin/task_dispensers/util.html b/inginious/frontend/templates/course_admin/task_dispensers/util.html
index 1fdf18c04..e063bc063 100644
--- a/inginious/frontend/templates/course_admin/task_dispensers/util.html
+++ b/inginious/frontend/templates/course_admin/task_dispensers/util.html
@@ -213,19 +213,6 @@ <h4>{{ _("Import from course filesystem") }}</h4>
             });
         });
 
-        $("#edit-modals .categories").each(function(){
-            $(this).selectize({
-                delimiter: ",",
-                persist: false,
-                create: function (input) {
-                    return {
-                    value: input,
-                    text: input,
-                    };
-                },
-            });
-        });
-
         dispenser_util_adapt_viewport();
         $(window).on( "resize", dispenser_util_adapt_viewport);
     });