diff --git a/README.md b/README.md
index db7abcb..d42b8ff 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,23 @@ best runtime available on the system.
 Use the application environment (application key: `:execjs`, key: `:runtime`)
 to set the runtime `Execjs` uses. Alternatively, the `EXECJS_RUNTIME`
 environment variable can also be used to set the runtime.
+### Additional Runtimes
+
+It is possible to define a custom runtime to specify an exact path
+to your runtime command:
+
+```elixir
+defmodule MyModule.Runtime do
+	import Execjs.Runtime
+
+	defruntime Node8,
+    		command: "/Users/o_o/.nvm/versions/node/v8.9.3/bin/node",
+		runner: "node_runner.js.eex"
+end
+
+```
+
+
 
 ## Usage
 
diff --git a/lib/execjs.ex b/lib/execjs.ex
index 252f2d4..9242230 100644
--- a/lib/execjs.ex
+++ b/lib/execjs.ex
@@ -35,7 +35,7 @@ defmodule Execjs do
 
     try do
       port = Port.open({ :spawn_executable, command },
-        [:stream, :in, :binary, :eof, :hide, { :args, [tmpfile] }])
+        [:stream, :in, :binary,:nouse_stdio, :eof, :hide, { :args, [tmpfile] }])
 
       extract_result(loop(port))
     after
diff --git a/priv/node_runner.js.eex b/priv/node_runner.js.eex
index 2b46b58..919a508 100644
--- a/priv/node_runner.js.eex
+++ b/priv/node_runner.js.eex
@@ -1,19 +1,24 @@
-(function(program, runner) { runner(program); })(function() {
-  return <%= source %>;
-}, function(program) {
-  var result;
-  try {
-    result = program();
-    try {
-      if (result === undefined) {
-        process.stdout.write('["ok"]');
-      } else {
-        process.stdout.write(JSON.stringify(['ok', result]));
-      }
-    } catch (err) {
-      process.stdout.write('["err"]');
+const fs = require('fs');
+(function(program, runner) {
+    runner(program);
+})(
+    function() {
+        return <%= source %>;
     }
-  } catch (err) {
-    process.stdout.write(JSON.stringify(['err', '' + err]));
-  }
-});
+    , async function(program) {
+        let result;
+        try {
+            result = await program();
+            try {
+                if (result === undefined) {
+                    fs.writeSync(4,'["ok"]');
+                } else {
+                    fs.writeSync(4,JSON.stringify(['ok', result]));
+                }
+            } catch (err) {
+               fs.writeSync(4, '["err"]');
+            }
+        } catch (err) {
+            fs.writeSync(4,JSON.stringify(['err', '' + err]));
+        }
+    });