diff --git a/reactos/include/defines.h b/reactos/include/defines.h
index 1e7742892f9..339b710135b 100644
--- a/reactos/include/defines.h
+++ b/reactos/include/defines.h
@@ -602,6 +602,10 @@ extern "C" {
 #define TAPE_SETMARKS	(0L)
 #define TAPE_SHORT_FILEMARKS	(0x2L)
 
+/* Mouse Wheel */
+#define WHEEL_DELTA (120)
+#define GET_WHEEL_DELTA_WPARAM(wParam)  ((short)HIWORD(wParam))
+
 /* CreateWindow */
 #define CW_USEDEFAULT	(0x80000000L)
 #define WS_BORDER	(0x800000L)
@@ -4336,6 +4340,8 @@ extern "C" {
 #define MK_MBUTTON	(16)
 #define MK_RBUTTON	(2)
 #define MK_SHIFT	(4)
+#define MK_XBUTTON1 (0x0020)
+#define MK_XBUTTON2 (0x0040)
 
 /* WNDCLASS structure */
 #define CS_BYTEALIGNCLIENT	(4096)
diff --git a/reactos/include/messages.h b/reactos/include/messages.h
index 84d665ffc9d..6547db9e785 100644
--- a/reactos/include/messages.h
+++ b/reactos/include/messages.h
@@ -1114,6 +1114,9 @@ extern "C" {
 #define WM_WINDOWPOSCHANGED	(71)
 #define WM_WINDOWPOSCHANGING	(70)
 #define WM_WININICHANGE	(26)
+#define WM_XBUTTONDOWN  (523)
+#define WM_XBUTTONUP    (524)
+#define WM_XBUTTONDBLCLK    (525)
 
 /* Window message ranges */
 #define WM_KEYFIRST	(256)