diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index 7c706fa..0624184 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -175,7 +175,8 @@
         if (ranges_overlap(md_addr, md_size, new_addr, size)) {
             if (hint) {
                 const DeviceState *d = DEVICE(md);
-                error_setg(errp, "address range conflicts with '%s'", d->id);
+                error_setg(errp, "address range conflicts with memory device"
+                           " id='%s'", d->id ? d->id : "(unnamed)");
                 goto out;
             }
             new_addr = QEMU_ALIGN_UP(md_addr + md_size, align);