diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index 53a99ae..0df7770 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -39,7 +39,7 @@
 
 	max_arg_len = 0;
 	for (i = 0; i < num_options; ++i)
-		max_arg_len = max(strlen(sb_opt[i]->flag), max_arg_len);
+		max_arg_len = max((int)strlen(sb_opt[i]->flag), max_arg_len);
 	max_noarg_len = max_arg_len + 7;
 
 	for (i = 0; i < num_options; ++i) {