diff --git a/arch/sandbox/lib/fdt_fixup.c b/arch/sandbox/lib/fdt_fixup.c
new file mode 100644
index 0000000..a646f20
--- /dev/null
+++ b/arch/sandbox/lib/fdt_fixup.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#define LOG_CATEGORY LOGC_ARCH
+
+#include <common.h>
+#include <fdt_support.h>
+#include <log.h>
+
+#if defined(__riscv)
+int arch_fixup_fdt(void *blob)
+{
+	int ret;
+
+	ret = fdt_find_or_add_subnode(blob, 0, "chosen");;
+	if (ret < 0)
+		goto err;
+	ret = fdt_setprop_u32(blob, ret, "boot-hartid", 1);
+	if (ret < 0)
+		goto err;
+	return 0;
+err:
+	log_err("Setting /chosen/boot-hartid failed: %s\n", fdt_strerror(ret));
+	return ret;
+}
+#endif