diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 18bd0e4bc36c..120b2f6f71bc 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -229,8 +229,8 @@ static void __init init_resources(void)
 	}
 
 	/* Clean-up any unused pre-allocated resources */
-	mem_res_sz = (num_resources - res_idx + 1) * sizeof(*mem_res);
-	memblock_free(__pa(mem_res), mem_res_sz);
+	if (res_idx >= 0)
+		memblock_free(__pa(mem_res), (res_idx + 1) * sizeof(*mem_res));
 	return;
 
  error: