diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index 0df7770..42353d8 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -130,7 +130,8 @@
 	state->write_ram_buf = true;
 	state->ram_buf_fname = arg;
 
-	if (os_read_ram_buf(arg)) {
+	err = os_read_ram_buf(arg);
+	if (err) {
 		printf("Failed to read RAM buffer\n");
 		return err;
 	}