diff --git a/ionic/components/button/button.ts b/ionic/components/button/button.ts
index bb7abca204..71535ddfa4 100644
--- a/ionic/components/button/button.ts
+++ b/ionic/components/button/button.ts
@@ -300,7 +300,7 @@ export class Button {
    */
   private _setClass(type: string, assignCssClass: boolean) {
     if (type && this._init) {
-      this._renderer.setElementClass(this._elementRef.nativeElement, this._role + '-' + type, assignCssClass);
+      this._renderer.setElementClass(this._elementRef.nativeElement, this._role + '-' + type.toLowerCase(), assignCssClass);
     }
   }