diff --git a/src/ATC/ATCdisplay.cxx b/src/ATC/ATCdisplay.cxx
index 78635152a..119f68201 100644
--- a/src/ATC/ATCdisplay.cxx
+++ b/src/ATC/ATCdisplay.cxx
@@ -22,6 +22,8 @@
 #  include <config.h>
 #endif
 
+#include <GL/glu.h>
+
 #include <simgear/props/props.hxx>
 
 #include <Include/general.hxx>
diff --git a/src/Cockpit/cockpit.cxx b/src/Cockpit/cockpit.cxx
index c6cb01eec..eaaafa603 100644
--- a/src/Cockpit/cockpit.cxx
+++ b/src/Cockpit/cockpit.cxx
@@ -29,6 +29,8 @@
 #  include <windows.h>
 #endif
 
+#include <GL/glu.h>
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
diff --git a/src/Cockpit/hud.cxx b/src/Cockpit/hud.cxx
index 60b4a14aa..110d982b0 100644
--- a/src/Cockpit/hud.cxx
+++ b/src/Cockpit/hud.cxx
@@ -44,6 +44,8 @@
 #include <stdio.h>		// char related functions
 #include <string.h>		// strcmp()
 
+#include <GL/glu.h>
+
 #include <simgear/constants.h>
 #include <simgear/debug/logstream.hxx>
 #include <simgear/props/props.hxx>
diff --git a/src/Cockpit/panel.cxx b/src/Cockpit/panel.cxx
index ad4465878..09194ef12 100644
--- a/src/Cockpit/panel.cxx
+++ b/src/Cockpit/panel.cxx
@@ -29,6 +29,8 @@
 #include <stdio.h>	// sprintf
 #include <string.h>
 
+#include <GL/glu.h>
+
 #include <plib/ssg.h>
 #include <plib/fnt.h>