diff --git a/libtcc.c b/libtcc.c
index 248dc7c..6d65e84 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -1936,6 +1936,10 @@ PUB_FUNC int tcc_parse_args(TCCState *s, int argc, char **argv)
             s->option_m = tcc_strdup(optarg);
             break;
         case TCC_OPTION_o:
+            if (s->outfile) {
+                tcc_warning("multiple -o option");
+                tcc_free(s->outfile);
+            }
             s->outfile = tcc_strdup(optarg);
             break;
         case TCC_OPTION_r: