diff --git a/src/msw/window.cpp b/src/msw/window.cpp
index 628d0b76ec..67b1e4d321 100644
--- a/src/msw/window.cpp
+++ b/src/msw/window.cpp
@@ -111,7 +111,11 @@
 #if wxUSE_MOUSEWHEEL
     #ifndef WM_MOUSEWHEEL
         #define WM_MOUSEWHEEL           0x020A
+    #endif
+    #ifndef WHEEL_DELTA
         #define WHEEL_DELTA             120
+    #endif
+    #ifndef SPI_GETWHEELSCROLLLINES
         #define SPI_GETWHEELSCROLLLINES 104
     #endif
 #endif