diff --git a/system/physmem.c b/system/physmem.c
index 5e6257ef65..b7847db1a2 100644
--- a/system/physmem.c
+++ b/system/physmem.c
@@ -2229,7 +2229,7 @@ static void *qemu_ram_ptr_length(RAMBlock *block, ram_addr_t addr,
          * because we don't want to map the entire memory in QEMU.
          * In that case just map the requested area.
          */
-        if (block->offset == 0) {
+        if (xen_mr_is_memory(block->mr)) {
             return xen_map_cache(block->mr, block->offset + addr,
                                  len, lock, lock,
                                  is_write);