diff --git a/hw/xwin/InitOutput.c b/hw/xwin/InitOutput.c
index ee1815c28..6e671d518 100644
--- a/hw/xwin/InitOutput.c
+++ b/hw/xwin/InitOutput.c
@@ -31,6 +31,9 @@ from The Open Group.
 #ifdef HAVE_XWIN_CONFIG_H
 #include <xwin-config.h>
 #endif
+
+#include "os/osdep.h"
+
 #include "win.h"
 #include "winmsg.h"
 #include "winconfig.h"
diff --git a/hw/xwin/winprocarg.c b/hw/xwin/winprocarg.c
index 35f12739c..9b79e543c 100644
--- a/hw/xwin/winprocarg.c
+++ b/hw/xwin/winprocarg.c
@@ -35,6 +35,8 @@ from The Open Group.
 #include <sys/utsname.h>
 #endif
 
+#include "os/osdep.h"
+
 #include <../xfree86/common/xorgVersion.h>
 #include "win.h"
 #include "winconfig.h"
diff --git a/include/os.h b/include/os.h
index 07ffde7ec..bbd9c8f22 100644
--- a/include/os.h
+++ b/include/os.h
@@ -93,12 +93,6 @@ typedef struct _NewClientRec *NewClientPtr;
 extern void ddxBeforeReset(void);
 #endif
 
-#ifdef DDXOSVERRORF
-extern _X_EXPORT void (*OsVendorVErrorFProc) (const char *,
-                                              va_list args)
-_X_ATTRIBUTE_PRINTF(1, 0);
-#endif
-
 extern _X_EXPORT Bool WaitForSomething(Bool clients_are_ready);
 
 extern _X_EXPORT int ReadRequestFromClient(ClientPtr /*client */ );
diff --git a/os/osdep.h b/os/osdep.h
index 677756624..ca6aa63b3 100644
--- a/os/osdep.h
+++ b/os/osdep.h
@@ -236,4 +236,10 @@ Bool OsLookupColor(int screen,
    depending on whether multithreading is used */
 int xthread_sigmask(int how, const sigset_t *set, sigset_t *oldest);
 
+#ifdef DDXOSVERRORF
+/* callback for DDX specific error printing, if any (may be NULL) */
+extern void (*OsVendorVErrorFProc) (const char *, va_list args)
+    _X_ATTRIBUTE_PRINTF(1, 0);
+#endif
+
 #endif                          /* _OSDEP_H_ */