diff --git a/src/arch/x86/include/ipxe/x86_io.h b/src/arch/x86/include/ipxe/x86_io.h
index 1fc7f660..9e68f4e7 100644
--- a/src/arch/x86/include/ipxe/x86_io.h
+++ b/src/arch/x86/include/ipxe/x86_io.h
@@ -28,6 +28,9 @@ FILE_LICENCE ( GPL2_OR_LATER );
  *
  */
 
+/** Page shift */
+#define PAGE_SHIFT 12
+
 /*
  * Physical<->Bus and Bus<->I/O address mappings
  *
diff --git a/src/include/ipxe/io.h b/src/include/ipxe/io.h
index b8b8aa31..29ccfd1f 100644
--- a/src/include/ipxe/io.h
+++ b/src/include/ipxe/io.h
@@ -23,6 +23,12 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <config/ioapi.h>
 #include <ipxe/uaccess.h>
 
+/** Page size */
+#define PAGE_SIZE ( 1 << PAGE_SHIFT )
+
+/** Page mask */
+#define PAGE_MASK ( PAGE_SIZE - 1 )
+
 /**
  * Calculate static inline I/O API function name
  *
diff --git a/src/include/ipxe/virtio-ring.h b/src/include/ipxe/virtio-ring.h
index 0afe8bab..c687acab 100644
--- a/src/include/ipxe/virtio-ring.h
+++ b/src/include/ipxe/virtio-ring.h
@@ -1,8 +1,5 @@
 #ifndef _VIRTIO_RING_H_
 # define _VIRTIO_RING_H_
-#define PAGE_SHIFT (12)
-#define PAGE_SIZE  (1<<PAGE_SHIFT)
-#define PAGE_MASK  (PAGE_SIZE-1)
 
 /* Status byte for guest to report progress, and synchronize features. */
 /* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */