diff --git a/test_suite/unit_tests/Autopilot/testDigitalFilter.cxx b/test_suite/unit_tests/Autopilot/testDigitalFilter.cxx
index cc337c12d..3594d8a1f 100644
--- a/test_suite/unit_tests/Autopilot/testDigitalFilter.cxx
+++ b/test_suite/unit_tests/Autopilot/testDigitalFilter.cxx
@@ -11,7 +11,7 @@
 #include <Main/globals.hxx>
 
 
-#include <simgear/math/sg_random.h>
+#include <simgear/math/sg_random.hxx>
 #include <simgear/props/props_io.hxx>
 
 // Set up function for each test.
diff --git a/test_suite/unit_tests/Autopilot/testPidController.cxx b/test_suite/unit_tests/Autopilot/testPidController.cxx
index 25608508c..a3cbbb9e5 100644
--- a/test_suite/unit_tests/Autopilot/testPidController.cxx
+++ b/test_suite/unit_tests/Autopilot/testPidController.cxx
@@ -10,7 +10,7 @@
 #include <Main/globals.hxx>
 
 
-#include <simgear/math/sg_random.h>
+#include <simgear/math/sg_random.hxx>
 #include <simgear/props/props_io.hxx>
 
 #include <unistd.h>