Index: machdep.c
===================================================================
RCS file: /cvsroot/src/sys/arch/vax/vax/machdep.c,v
retrieving revision 1.202
diff -u -p -r1.202 machdep.c
--- machdep.c	30 Nov 2025 01:31:35 -0000	1.202
+++ machdep.c	27 Apr 2026 23:09:53 -0000
@@ -324,8 +324,8 @@ consinit(void)
 	KASSERT(iomap_arena != NULL);
 
 	vmem_add_bts(iomap_arena, iomap_btag_store, IOMAP_BTAG_COUNT);
-	int error = vmem_add(iomap_arena, iospace, IOSPSZ * VAX_NBPG,
-	    VM_NOSLEEP);
+	int error = vmem_add(iomap_arena, iospace + VAX_NBPG,
+	    (IOSPSZ * VAX_NBPG) - 1, VM_NOSLEEP);
 	KASSERT(error == 0);
 #ifdef DEBUG
 	iospace_inited = 1;