diff --git a/lib/compiler.js b/lib/compiler.js
index eeca92b9..80cc8612 100644
--- a/lib/compiler.js
+++ b/lib/compiler.js
@@ -1,11 +1,23 @@
 /*jshint esversion: 6, loopfunc: true */
 var solc = require('solc');
+var async = require('async');
+
+function asyncEachObject(object, iterator, callback) {
+  async.each(
+    Object.keys(object || {}),
+    function(key, next){
+      iterator(key, object[key], next);
+    },
+    callback
+  );
+}
+async.eachObject = asyncEachObject;
 
 var Compiler = function(options) {
   this.plugins = options.plugins;
 };
 
-Compiler.prototype.compile_contracts = function(contractFiles) {
+Compiler.prototype.compile_contracts = function(contractFiles, cb) {
 
   var available_compilers = {
     //".se": this.compile_serpent
@@ -25,20 +37,25 @@ Compiler.prototype.compile_contracts = function(contractFiles) {
 
   var compiledObject = {};
 
-  // TODO: warn about files it doesn't know how to compile
-  for (var extension in available_compilers) {
-    var compiler = available_compilers[extension];
-    var matchingFiles = contractFiles.filter(function(file) {
-      return (file.filename.match(/\.[0-9a-z]+$/)[0] === extension);
-    });
+  async.eachObject(available_compilers,
+    function(extension, compiler, callback) {
+      // TODO: warn about files it doesn't know how to compile
+      var matchingFiles = contractFiles.filter(function(file) {
+        return (file.filename.match(/\.[0-9a-z]+$/)[0] === extension);
+      });
 
-    Object.assign(compiledObject, compiler.call(compiler, matchingFiles || []));
-  }
-
-  return compiledObject;
+      compiler.call(compiler, matchingFiles || [], function(compileResult) {
+        Object.assign(compiledObject, compileResult);
+        callback();
+      });
+    },
+    function (err) {
+      cb(compiledObject);
+    }
+  );
 };
 
-Compiler.prototype.compile_solidity = function(contractFiles) {
+Compiler.prototype.compile_solidity = function(contractFiles, cb) {
   var input = {};
 
   for (var i = 0; i < contractFiles.length; i++){
@@ -68,7 +85,7 @@ Compiler.prototype.compile_solidity = function(contractFiles) {
     compiled_object[className].abiDefinition   = JSON.parse(contract.interface);
   }
 
-  return compiled_object;
+  cb(compiled_object);
 };
 
 module.exports = Compiler;
diff --git a/lib/contracts.js b/lib/contracts.js
index 369fdb45..d8bfd51e 100644
--- a/lib/contracts.js
+++ b/lib/contracts.js
@@ -39,12 +39,15 @@ ContractsManager.prototype.build = function(done) {
   async.waterfall([
     function compileContracts(callback) {
       var compiler = new Compiler({plugins: self.plugins});
+      // TODO: check if try is still needed
       try {
-        self.compiledContracts = compiler.compile_contracts(self.contractFiles);
+        compiler.compile_contracts(self.contractFiles, function(compiledObject) {
+          self.compiledContracts = compiledObject;
+          callback();
+        });
       } catch(err) {
         return callback(new Error(err.message));
       }
-      return callback();
     },
     function prepareContractsFromConfig(callback) {
       var className, contract;
diff --git a/test/compiler.js b/test/compiler.js
index d39b9993..e5e6724c 100644
--- a/test/compiler.js
+++ b/test/compiler.js
@@ -11,19 +11,20 @@ describe('embark.Compiler', function() {
   var compiler = new Compiler({});
 
   describe('#compile_solidity', function() {
-    var compiledContracts = compiler.compile_solidity([
-      readFile('test/contracts/simple_storage.sol'),
-      readFile('test/contracts/token.sol')
-    ]);
-
     var expectedObject = {};
 
     expectedObject["SimpleStorage"] = {"code":"606060405234610000576040516020806100f083398101604052515b60008190555b505b60bf806100316000396000f300606060405263ffffffff60e060020a6000350416632a1afcd98114603657806360fe47b11460525780636d4ce63c146061575b6000565b346000576040607d565b60408051918252519081900360200190f35b34600057605f6004356083565b005b346000576040608c565b60408051918252519081900360200190f35b60005481565b60008190555b50565b6000545b905600a165627a7a72305820a250be048d43f54e9afbb37211dc73ba843d23b95863b60afe703903500077220029","runtimeBytecode":"606060405263ffffffff60e060020a6000350416632a1afcd98114603657806360fe47b11460525780636d4ce63c146061575b6000565b346000576040607d565b60408051918252519081900360200190f35b34600057605f6004356083565b005b346000576040608c565b60408051918252519081900360200190f35b60005481565b60008190555b50565b6000545b905600a165627a7a72305820a250be048d43f54e9afbb37211dc73ba843d23b95863b60afe703903500077220029","gasEstimates":{"creation":[20131,38200],"external":{"get()":269,"set(uint256)":20163,"storedData()":224},"internal":{}},"functionHashes":{"get()":"6d4ce63c","set(uint256)":"60fe47b1","storedData()":"2a1afcd9"},"abiDefinition":[{"constant":true,"inputs":[],"name":"storedData","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"x","type":"uint256"}],"name":"set","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"retVal","type":"uint256"}],"payable":false,"type":"function"},{"inputs":[{"name":"initialValue","type":"uint256"}],"payable":false,"type":"constructor"}]};
 
     expectedObject["Token"] = {"code":"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","runtimeBytecode":"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","gasEstimates":{"creation":[40422,217800],"external":{"allowance(address,address)":598,"approve(address,uint256)":22273,"balanceOf(address)":462,"totalSupply()":265,"transfer(address,uint256)":42894,"transferFrom(address,address,uint256)":63334},"internal":{"safeToAdd(uint256,uint256)":41}},"functionHashes":{"allowance(address,address)":"dd62ed3e","approve(address,uint256)":"095ea7b3","balanceOf(address)":"70a08231","totalSupply()":"18160ddd","transfer(address,uint256)":"a9059cbb","transferFrom(address,address,uint256)":"23b872dd"},"abiDefinition":[{"constant":false,"inputs":[{"name":"spender","type":"address"},{"name":"value","type":"uint256"}],"name":"approve","outputs":[{"name":"ok","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"supply","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"from","type":"address"},{"name":"to","type":"address"},{"name":"value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"ok","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"who","type":"address"}],"name":"balanceOf","outputs":[{"name":"value","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"to","type":"address"},{"name":"value","type":"uint256"}],"name":"transfer","outputs":[{"name":"ok","type":"bool"}],"payable":false,"type":"function"},{"constant":true,"inputs":[{"name":"owner","type":"address"},{"name":"spender","type":"address"}],"name":"allowance","outputs":[{"name":"_allowance","type":"uint256"}],"payable":false,"type":"function"},{"inputs":[{"name":"initial_balance","type":"uint256"}],"payable":false,"type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"owner","type":"address"},{"indexed":true,"name":"spender","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Approval","type":"event"}]}
 
-    it('should generate compiled code and abi', function() {
-      assert.deepEqual(compiledContracts, expectedObject);
+    it('should generate compiled code and abi', function(done) {
+      compiler.compile_solidity([
+        readFile('test/contracts/simple_storage.sol'),
+        readFile('test/contracts/token.sol')
+      ], function(compiledContracts) {
+        assert.deepEqual(compiledContracts, expectedObject);
+        done();
+      });
     });
 
   });