diff --git a/qjs.c b/qjs.c
index be8a21d..60a6dcd 100644
--- a/qjs.c
+++ b/qjs.c
@@ -531,7 +531,7 @@ int main(int argc, char **argv)
                  "\n"
                  "if (typeof os !== 'undefined') {\n"
                  "    globalThis.sleep = os.sleep;\n"
-                 "    async function setTimeout(func, ms) { await sleep(ms); Function(func)(); }\n"
+                 "    async function setTimeout(func, ms) { await sleep(ms); return func(); }\n"
                  "    globalThis.setTimeout = setTimeout\n"
                  "} else {\n"
                  "    console.error('os is not defined.');\n"