diff --git a/include/wingdi.h b/include/wingdi.h
index 71abf76a0db..bff2f136cee 100644
--- a/include/wingdi.h
+++ b/include/wingdi.h
@@ -416,7 +416,7 @@ DECL_WINELIB_TYPE_AW(LOGCOLORSPACE)
 
   /* Colors */
 
-#define RGB(r,g,b)          ((COLORREF)((r) | ((g) << 8) | ((b) << 16)))
+#define RGB(r,g,b)          ((COLORREF)((BYTE)(r) | ((BYTE)(g) << 8) | ((BYTE)(b) << 16)))
 #define PALETTERGB(r,g,b)   (0x02000000 | RGB(r,g,b))
 #define PALETTEINDEX(i)     ((COLORREF)(0x01000000 | (WORD)(i)))