diff --git a/src/js/easymde.js b/src/js/easymde.js
index f4a0c70..20a6c40 100644
--- a/src/js/easymde.js
+++ b/src/js/easymde.js
@@ -219,6 +219,16 @@ function createToolbarDropdown(options, enableTooltips, shortcuts, parent) {
 function createToolbarButton(options, enableActions, enableTooltips, shortcuts, markup, parent) {
     options = options || {};
     var el = document.createElement(markup);
+
+    // Add 'custom' attributes as early as possible, so that 'official' attributes will never be overwritten.
+    if (options.attributes) {
+        for (var attribute in options.attributes) {
+            if (Object.prototype.hasOwnProperty.call(options.attributes, attribute)) {
+                el.setAttribute(attribute, options.attributes[attribute]);
+            }
+        }
+    }
+
     el.className = options.name;
     el.setAttribute('type', markup);
     enableTooltips = (enableTooltips == undefined) ? true : enableTooltips;
@@ -237,14 +247,6 @@ function createToolbarButton(options, enableActions, enableTooltips, shortcuts,
         }
     }
 
-    if (options.attributes) {
-        for (var attribute in options.attributes) {
-            if (Object.prototype.hasOwnProperty.call(options.attributes, attribute)) {
-                el.setAttribute(attribute, options.attributes[attribute]);
-            }
-        }
-    }
-
     if (options.noDisable) {
         el.classList.add('no-disable');
     }