diff --git a/lib/modules/vyper/index.js b/lib/modules/vyper/index.js
index 6e11d0b33..f8ca1760e 100644
--- a/lib/modules/vyper/index.js
+++ b/lib/modules/vyper/index.js
@@ -14,13 +14,15 @@ class Vyper {
     embark.registerCompiler(".vy", this.compile_vyper.bind(this));
   }
 
-  static compileVyperContract(filename, compileABI, callback) {
-    const params = compileABI ?  '-f json ' : '';
+  compileVyperContract(filename, compileABI, callback) {
+    const self = this;
+    const params = compileABI ?  '-f=json ' : '';
     shelljs.exec(`vyper ${params}${filename}`, {silent: true}, (code, stdout, stderr) => {
       if (stderr) {
         return callback(stderr);
       }
       if (code !== 0) {
+        self.logger.error(stdout);
         return callback(__('Vyper exited with error code ') + code);
       }
       if (!stdout) {
@@ -31,7 +33,7 @@ class Vyper {
   }
 
   compile_vyper(contractFiles, cb) {
-    let self = this;
+    const self = this;
     if (!contractFiles || !contractFiles.length) {
       return cb();
     }
@@ -51,7 +53,7 @@ class Vyper {
         compiled_object[className] = {};
         async.parallel([
           function getByteCode(paraCb) {
-            Vyper.compileVyperContract(file.filename, false, (err, byteCode) => {
+            self.compileVyperContract(file.filename, false, (err, byteCode) => {
               if (err) {
                 return paraCb(err);
               }
@@ -62,7 +64,7 @@ class Vyper {
             });
           },
           function getABI(paraCb) {
-            Vyper.compileVyperContract(file.filename, true, (err, ABIString) => {
+            self.compileVyperContract(file.filename, true, (err, ABIString) => {
               if (err) {
                 return paraCb(err);
               }