diff --git a/hw/ssi/aspeed_smc.c b/hw/ssi/aspeed_smc.c
index 1270842dcf..7af808c33c 100644
--- a/hw/ssi/aspeed_smc.c
+++ b/hw/ssi/aspeed_smc.c
@@ -670,7 +670,7 @@ static uint64_t aspeed_smc_read(void *opaque, hwaddr addr, unsigned int size)
     } else {
         qemu_log_mask(LOG_UNIMP, "%s: not implemented: 0x%" HWADDR_PRIx "\n",
                       __func__, addr);
-        return 0;
+        return -1;
     }
 }