diff --git a/simgear/environment/visual_enviro.cxx b/simgear/environment/visual_enviro.cxx
index 2c85ec9c..533293bb 100644
--- a/simgear/environment/visual_enviro.cxx
+++ b/simgear/environment/visual_enviro.cxx
@@ -26,7 +26,7 @@
 #include <simgear/constants.h>
 #include <simgear/structure/SGReferenced.hxx>
 #include <simgear/structure/SGSharedPtr.hxx>
-#include <simgear/math/sg_random.h>
+#include <simgear/math/sg_random.hxx>
 #include <simgear/math/sg_geodesy.hxx>
 #include <simgear/sound/sample_group.hxx>
 #include <simgear/scene/sky/cloudfield.hxx>