diff --git a/lib/command/spawn.js b/lib/command/spawn.js
index 2e10c95..4895bb3 100644
--- a/lib/command/spawn.js
+++ b/lib/command/spawn.js
@@ -20,7 +20,7 @@ inherits(Command, ParentCommand);
  */
 Command.prototype.run = function(params, callback) {
 	var self = this,
-		stdout = '';
+		stdout = self.isCollect ? '' : null;
 	if (!params.cmd) return callback(new Error('`cmd` is not set'));
 	if (!params.args) return callback(new Error('`args` is not set'));
 	callback = utils.once(callback);
@@ -29,8 +29,7 @@ Command.prototype.run = function(params, callback) {
 	var cmd = spawn(params.cmd, params.args, params.options);
 	cmd.stdout.on('data', function(data) {
 		if (self.isEmit) self.emit('stdout', data);
-		// TODO: join stdout only if flag is set
-		stdout += data;
+		if (self.isCollect) stdout += data;
 	});
 	cmd.stderr.on('data', function(data) {
 		callback(new Error('Spawned command outputs to stderr: ' + data));
diff --git a/lib/scm/base.js b/lib/scm/base.js
index 6531b49..ee5bbae 100644
--- a/lib/scm/base.js
+++ b/lib/scm/base.js
@@ -9,6 +9,7 @@ function Scm(params) {
 	if (!this.repository && !this.cwd) throw new Error(
 		'`repository` or `cwd` must be set'
 	);
+	this.isCollect = true;
 }
 
 exports.Scm = Scm;