diff --git a/src/ui/CSimpleSlider.hpp b/src/ui/CSimpleSlider.hpp
index 41b9304..f5f3a4e 100644
--- a/src/ui/CSimpleSlider.hpp
+++ b/src/ui/CSimpleSlider.hpp
@@ -24,6 +24,7 @@ class CSimpleSlider : public CSimpleFrame {
         float m_value = 0.0f;
         float m_valueStep = 0.0f;
         CSimpleTexture* m_thumbTexture = nullptr;
+        SLIDER_ORIENTATION m_orientation = SLIDER_VERTICAL;
         ScriptIx m_onValueChanged;
         ScriptIx m_onMinMaxChanged;
 
diff --git a/src/ui/Types.hpp b/src/ui/Types.hpp
index fe0274e..7dbb53c 100644
--- a/src/ui/Types.hpp
+++ b/src/ui/Types.hpp
@@ -88,6 +88,11 @@ enum PLURAL_RULE {
     PLURAL_RULE_2   = 2
 };
 
+enum SLIDER_ORIENTATION {
+    SLIDER_HORIZONTAL       = 0,
+    SLIDER_VERTICAL         = 1,
+};
+
 enum TextureImageMode {
     ImageMode_UI            = 0,
     ImageMode_Desaturate    = 1