diff --git a/src/widget_type.h b/src/widget_type.h
index 2c3b539622..a7a9812c7f 100644
--- a/src/widget_type.h
+++ b/src/widget_type.h
@@ -172,7 +172,7 @@ enum SizingType {
 
 /* Forward declarations. */
 class NWidgetCore;
-struct Scrollbar;
+class Scrollbar;
 
 /**
  * Baseclass for nested widgets.