diff --git a/libraries/AP_HAL_ChibiOS/Scheduler.cpp b/libraries/AP_HAL_ChibiOS/Scheduler.cpp
index b22293383bf8b0..4b8341640ca4ee 100644
--- a/libraries/AP_HAL_ChibiOS/Scheduler.cpp
+++ b/libraries/AP_HAL_ChibiOS/Scheduler.cpp
@@ -42,6 +42,7 @@
 #if CH_CFG_USE_DYNAMIC == TRUE
 
 #include <AP_Logger/AP_Logger.h>
+#include <AP_Math/AP_Math.h>
 #include <AP_Scheduler/AP_Scheduler.h>
 #include <AP_BoardConfig/AP_BoardConfig.h>
 #include "hwdef/common/stm32_util.h"