diff --git a/tools/api-tester/apitest.js b/tools/api-tester/apitest.js
index 383d5703..46759541 100644
--- a/tools/api-tester/apitest.js
+++ b/tools/api-tester/apitest.js
@@ -35,7 +35,7 @@ try {
         unit,
     }, positionals: [id] } = parsed);
 
-    onlycase = Number.parseInt(onlycase);
+    onlycase = onlycase !== undefined ? Number.parseInt(onlycase) : undefined;
 } catch (e) {
     console.error(e);
     console.error(