diff --git a/libraries/SITL/SIM_GPS_MSP.cpp b/libraries/SITL/SIM_GPS_MSP.cpp
index 1751b5bdbd..125f1b8de2 100644
--- a/libraries/SITL/SIM_GPS_MSP.cpp
+++ b/libraries/SITL/SIM_GPS_MSP.cpp
@@ -6,6 +6,8 @@
 
 #include <SITL/SITL.h>
 
+#include <time.h>
+
 using namespace SITL;
 
 /*
diff --git a/libraries/SITL/SIM_GPS_NMEA.cpp b/libraries/SITL/SIM_GPS_NMEA.cpp
index 0491cce2eb..161f0ef0f0 100644
--- a/libraries/SITL/SIM_GPS_NMEA.cpp
+++ b/libraries/SITL/SIM_GPS_NMEA.cpp
@@ -8,6 +8,8 @@
 #include <AP_Common/NMEA.h>
 #include <AP_HAL/AP_HAL.h>
 
+#include <time.h>
+
 extern const AP_HAL::HAL& hal;
 
 using namespace SITL;
diff --git a/libraries/SITL/SIM_GPS_Trimble.cpp b/libraries/SITL/SIM_GPS_Trimble.cpp
index 6c3b41c80c..9ddaf64027 100644
--- a/libraries/SITL/SIM_GPS_Trimble.cpp
+++ b/libraries/SITL/SIM_GPS_Trimble.cpp
@@ -6,6 +6,7 @@
 
 #include <SITL/SITL.h>
 #include <AP_HAL/utility/sparse-endian.h>
+#include <AP_InternalError/AP_InternalError.h>
 
 #include <assert.h>