diff --git a/gui-builder/include/GuiBuilder.hpp b/gui-builder/include/GuiBuilder.hpp
index 160d2c954..a4c85ba46 100644
--- a/gui-builder/include/GuiBuilder.hpp
+++ b/gui-builder/include/GuiBuilder.hpp
@@ -51,7 +51,7 @@
 class GuiBuilder
 {
 public:
-    enum class UndoType
+    enum class UndoType : uint8_t
     {
         Delete,
         Move,