diff --git a/simgear/ephemeris/ephemeris.hxx b/simgear/ephemeris/ephemeris.hxx
index 74594e3b..f6658edd 100644
--- a/simgear/ephemeris/ephemeris.hxx
+++ b/simgear/ephemeris/ephemeris.hxx
@@ -26,6 +26,10 @@
 #define _EPHEMERIS_HXX
 
 
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
 #include <plib/sg.h>
 
 #include <Time/fg_time.hxx>
diff --git a/simgear/sky/moon.cxx b/simgear/sky/moon.cxx
index d4e8883c..54751991 100644
--- a/simgear/sky/moon.cxx
+++ b/simgear/sky/moon.cxx
@@ -24,6 +24,10 @@
 // $Id$
 
 
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
 #include <stdio.h>
 #include <iostream>
 
diff --git a/simgear/sky/oursun.cxx b/simgear/sky/oursun.cxx
index 80d12c07..0761fc50 100644
--- a/simgear/sky/oursun.cxx
+++ b/simgear/sky/oursun.cxx
@@ -24,6 +24,10 @@
 // $Id$
 
 
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
 #include <stdio.h>
 #include <iostream>
 
diff --git a/simgear/sky/sky.cxx b/simgear/sky/sky.cxx
index 3033e3b7..eb86def9 100644
--- a/simgear/sky/sky.cxx
+++ b/simgear/sky/sky.cxx
@@ -22,6 +22,10 @@
 // $Id$
 
 
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
 #include <plib/ssg.h>		// plib include
 
 #include "sky.hxx"
diff --git a/simgear/sky/sphere.cxx b/simgear/sky/sphere.cxx
index d43cbc85..fc20bee1 100644
--- a/simgear/sky/sphere.cxx
+++ b/simgear/sky/sphere.cxx
@@ -22,6 +22,10 @@
 // $Id$
 
 
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
 #include <plib/ssg.h>
 
 
diff --git a/simgear/sky/stars.cxx b/simgear/sky/stars.cxx
index 62a99bcf..2b194b7f 100644
--- a/simgear/sky/stars.cxx
+++ b/simgear/sky/stars.cxx
@@ -24,6 +24,10 @@
 // $Id$
 
 
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
 #include <stdio.h>
 #include <iostream>