diff --git a/libraries/AP_Math/examples/rotations/rotations.pde b/libraries/AP_Math/examples/rotations/rotations.pde
index 7ebe620e8d..f3fd66510e 100644
--- a/libraries/AP_Math/examples/rotations/rotations.pde
+++ b/libraries/AP_Math/examples/rotations/rotations.pde
@@ -35,6 +35,7 @@
 #include <AP_Rally.h>
 #include <AP_BattMonitor.h>
 #include <AP_RangeFinder.h>
+#include <AP_OpticalFlow.h>
 
 const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;