diff --git a/sys/x86/include/xen/xen-os.h b/sys/x86/include/xen/xen-os.h
--- a/sys/x86/include/xen/xen-os.h
+++ b/sys/x86/include/xen/xen-os.h
@@ -33,6 +33,9 @@
 /* Everything below this point is not included by assembler (.S) files. */
 #ifndef __ASSEMBLY__
 
+/* If non-zero, the hypervisor has been configured to use a direct vector */
+extern int xen_vector_callback_enabled;
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _MACHINE_X86_XEN_XEN_OS_H_ */
diff --git a/sys/xen/xen_intr.h b/sys/xen/xen_intr.h
--- a/sys/xen/xen_intr.h
+++ b/sys/xen/xen_intr.h
@@ -38,9 +38,6 @@
 /** Registered Xen interrupt callback handle. */
 typedef void * xen_intr_handle_t;
 
-/** If non-zero, the hypervisor has been configured to use a direct vector */
-extern int xen_vector_callback_enabled;
-
 void xen_intr_handle_upcall(struct trapframe *trap_frame);
 
 /**