diff --git a/hwaccess.c b/hwaccess.c
index acb99f8..bb5aac4 100644
--- a/hwaccess.c
+++ b/hwaccess.c
@@ -223,7 +223,7 @@
 	};
 };
 
-int undo_mmio_write(void *p)
+static int undo_mmio_write(void *p)
 {
 	struct undo_mmio_write_data *data = p;
 	msg_pdbg("Restoring MMIO space at %p\n", data->addr);