diff --git a/code/sdl/sdl_input.c b/code/sdl/sdl_input.c
index bce410a7..b826678c 100644
--- a/code/sdl/sdl_input.c
+++ b/code/sdl/sdl_input.c
@@ -42,6 +42,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #endif
 
 #ifdef MACOS_X_ACCELERATION_HACK
+#include <IOKit/hidsystem/IOTypes.h>
 #include <IOKit/hidsystem/IOHIDLib.h>
 #include <IOKit/hidsystem/IOHIDParameter.h>
 #include <IOKit/hidsystem/event_status_driver.h>