diff --git a/po/po2json b/po/po2json
index 67cedde..d521f30 100755
--- a/po/po2json
+++ b/po/po2json
@@ -25,8 +25,8 @@ var argi = 2;
 var filename = null;
 
 var opts = stdio.getopt({
-    module: { key: "m", args: 1, description: "Module template to include" },
-    output: { key: "o", args: 1, description: "Output file" },
+    module: { key: "m", args: 1, description: "Module template to include", default: "" },
+    output: { key: "o", args: 1, description: "Output file", default: "" },
 });
 
 if (opts.args.length != 1) {