diff --git a/src/Environment/environment.cxx b/src/Environment/environment.cxx
index f99c31e09..050bededb 100644
--- a/src/Environment/environment.cxx
+++ b/src/Environment/environment.cxx
@@ -36,8 +36,11 @@
 #include <simgear/constants.h>
 #include <simgear/debug/logstream.hxx>
 #include <simgear/math/interpolater.hxx>
+#include <simgear/props/props.hxx>
 #include <simgear/environment/visual_enviro.hxx>
 
+#include <Main/fg_props.hxx>
+
 #include "environment.hxx"