diff --git a/src/test/Makefile b/src/test/Makefile
index fd0266e1dd..92ca4f1c16 100644
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -105,17 +105,20 @@ battery_unittest : $(OBJECT_DIR)/sensors/battery.o $(OBJECT_DIR)/battery_unittes
 
 
 
+$(OBJECT_DIR)/flight/altitudehold.o : $(USER_DIR)/flight/altitudehold.c $(USER_DIR)/flight/altitudehold.h $(GTEST_HEADERS)
+	@mkdir -p $(dir $@)
+	$(CC) $(CPPFLAGS) $(CXXFLAGS) $(TEST_CFLAGS) -c $(USER_DIR)/flight/altitudehold.c -o $@
 
 $(OBJECT_DIR)/flight/imu.o : $(USER_DIR)/flight/imu.c $(USER_DIR)/flight/imu.h $(GTEST_HEADERS)
 	@mkdir -p $(dir $@)
-	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(TEST_CFLAGS) -c $(USER_DIR)/flight/imu.c -o $@
+	$(CC) $(CPPFLAGS) $(CXXFLAGS) $(TEST_CFLAGS) -c $(USER_DIR)/flight/imu.c -o $@
 
 $(OBJECT_DIR)/flight_imu_unittest.o : $(TEST_DIR)/flight_imu_unittest.cc \
                      $(USER_DIR)/flight/imu.h $(GTEST_HEADERS)
 	@mkdir -p $(dir $@)
 	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(TEST_CFLAGS) -c $(TEST_DIR)/flight_imu_unittest.cc -o $@
 
-flight_imu_unittest : $(OBJECT_DIR)/flight/imu.o $(OBJECT_DIR)/flight_imu_unittest.o $(OBJECT_DIR)/gtest_main.a
+flight_imu_unittest : $(OBJECT_DIR)/flight/imu.o $(OBJECT_DIR)/flight/altitudehold.o $(OBJECT_DIR)/flight_imu_unittest.o $(OBJECT_DIR)/gtest_main.a
 	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -lpthread $^ -o $(OBJECT_DIR)/$@
 
 
diff --git a/src/test/unit/flight_imu_unittest.cc b/src/test/unit/flight_imu_unittest.cc
index a59f810dd5..50c35918d9 100644
--- a/src/test/unit/flight_imu_unittest.cc
+++ b/src/test/unit/flight_imu_unittest.cc
@@ -22,20 +22,23 @@
 
 #define BARO
 
-#include "common/axis.h"
-#include "flight/flight.h"
+extern "C" {
+    #include "common/axis.h"
+    #include "flight/flight.h"
+    #include "flight/altitudehold.h"
 
-#include "sensors/sensors.h"
-#include "drivers/accgyro.h"
-#include "sensors/gyro.h"
-#include "sensors/compass.h"
-#include "sensors/acceleration.h"
-#include "sensors/barometer.h"
+    #include "sensors/sensors.h"
+    #include "drivers/accgyro.h"
+    #include "sensors/gyro.h"
+    #include "sensors/compass.h"
+    #include "sensors/acceleration.h"
+    #include "sensors/barometer.h"
 
-#include "config/runtime_config.h"
+    #include "config/runtime_config.h"
 
-#include "flight/mixer.h"
-#include "flight/imu.h"
+    #include "flight/mixer.h"
+    #include "flight/imu.h"
+}
 
 #include "unittest_macros.h"
 #include "gtest/gtest.h"
@@ -44,7 +47,9 @@
 #define UPWARDS_THRUST false
 
 
-bool isThrustFacingDownwards(rollAndPitchInclination_t *inclinations);
+extern "C" {
+    bool isThrustFacingDownwards(rollAndPitchInclination_t *inclinations);
+}
 
 typedef struct inclinationExpectation_s {
     rollAndPitchInclination_t inclination;
@@ -82,6 +87,8 @@ TEST(FlightImuTest, IsThrustFacingDownwards)
 
 // STUBS
 
+extern "C" {
+
 uint16_t acc_1G;
 int16_t heading;
 gyro_t gyro;
@@ -118,3 +125,5 @@ int constrain(int amt, int low, int high)
     UNUSED(high);
     return 0;
 }
+
+}