diff --git a/cli.js b/cli.js
index 99131c7..88be9f5 100755
--- a/cli.js
+++ b/cli.js
@@ -30,10 +30,8 @@ const version = require("./package").version;
 
 const argv = require("yargs")
     .version(version)
-    .usage("circom -s [input source circuit file] -o [output definition circuit file]")
-    .alias("s", "source")
+    .usage("circom [input source circuit file] -o [output definition circuit file]")
     .alias("o", "output")
-    .require(["s","o"])
     .help("h")
     .alias("h", "help")
     .epilogue(`Copyright (C) 2018  0kims association
@@ -43,10 +41,11 @@ const argv = require("yargs")
     repo directory at  https://github.com/iden3/circom `)
     .argv;
 
-const fullFileName = path.resolve(process.cwd(), argv.source);
+const fullFileName = path.resolve(process.cwd(), argv._[0]);
+const outName = argv.output ?  argv.output : "circuit.json";
 
 compiler(fullFileName).then( (cir) => {
-    fs.writeFileSync(argv.output, JSON.stringify(cir, null, 1), "utf8");
+    fs.writeFileSync(outName, JSON.stringify(cir, null, 1), "utf8");
 }, (err) => {
     console.log(err);
     console.error(`ERROR at ${err.errFile}:${err.pos.first_line},${err.pos.first_column}-${err.pos.last_line},${err.pos.last_column}   ${err.errStr}`);
diff --git a/package-lock.json b/package-lock.json
index 93a1a0c..3d779f6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1469,14 +1469,15 @@
       }
     },
     "snarkjs": {
-      "version": "0.1.0",
-      "resolved": "https://registry.npmjs.org/snarkjs/-/snarkjs-0.1.0.tgz",
-      "integrity": "sha512-i+OOKwATef3/oUleae9FHt/qACPYH1M5gjQkdYYkyRYqScIuZHCmNSf6Q5RWJT5hmOkTEor+T2C5qwKSrzzGSg==",
+      "version": "0.1.3",
+      "resolved": "https://registry.npmjs.org/snarkjs/-/snarkjs-0.1.3.tgz",
+      "integrity": "sha512-z5HhuNt019ZzNzUztETK31rpjRRSz3Uzy8TjGgSROf+9ZT9i6dbdWkjTC3fh5o9H+R/2+hcR+7IKAmpIR56V+A==",
       "dev": true,
       "requires": {
         "big-integer": "^1.6.35",
         "chai": "^4.1.2",
-        "eslint": "^5.3.0"
+        "eslint": "^5.3.0",
+        "yargs": "^12.0.2"
       },
       "dependencies": {
         "ajv": {