diff --git a/deps/libui/win32/slider.cpp b/deps/libui/win32/slider.cpp
index 5c671dda09..b388ebc635 100644
--- a/deps/libui/win32/slider.cpp
+++ b/deps/libui/win32/slider.cpp
@@ -1,6 +1,10 @@
 // 20 may 2015
 #include "uipriv_windows.hpp"
 
+#ifndef TBS_TRANSPARENTBKGND
+#define TBS_TRANSPARENTBKGND 0x1000
+#endif
+
 struct uiSlider {
 	uiWindowsControl c;
 	HWND hwnd;