diff --git a/extmidi.c b/extmidi.c
--- a/extmidi.c
+++ b/extmidi.c
@@ -2,7 +2,7 @@
 #ifndef __MORPHOS__
 #include "stdafx.h"
 
-#include "ttd.h"
+#include "openttd.h"
 #include "hal.h"
 #include "sound.h"
 #include "string.h"
diff --git a/os/beos/bemidi.cpp b/os/beos/bemidi.cpp
--- a/os/beos/bemidi.cpp
+++ b/os/beos/bemidi.cpp
@@ -1,7 +1,7 @@
 #ifdef __BEOS__
 
 #include "stdafx.h"
-#include "ttd.h"
+#include "openttd.h"
 #include "hal.h"
 
 // BeOS System Includes
diff --git a/os2.c b/os2.c
--- a/os2.c
+++ b/os2.c
@@ -1,5 +1,5 @@
 #include "stdafx.h"
-#include "ttd.h"
+#include "openttd.h"
 #include "window.h"
 #include "string.h"
 #include "table/strings.h"
diff --git a/unix.c b/unix.c
--- a/unix.c
+++ b/unix.c
@@ -1,5 +1,5 @@
 #include "stdafx.h"
-#include "ttd.h"
+#include "openttd.h"
 #include "window.h"
 #include "string.h"
 #include "table/strings.h"