diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
index 2ecfe4f700d9..9aa8988cb340 100644
--- a/include/xen/interface/memory.h
+++ b/include/xen/interface/memory.h
@@ -160,6 +160,7 @@ DEFINE_GUEST_HANDLE_STRUCT(xen_machphys_mapping_t);
 #define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another dom,
 				    * XENMEM_add_to_physmap_range only.
 				    */
+#define XENMAPSPACE_dev_mmio     5 /* device mmio region */
 
 /*
  * Sets the GPFN at which a particular page appears in the specified guest's