@@ -16,7 +16,6 @@ import (

 	"path/filepath"

 	"sort"

 	"strings"

-	"sync"

 	"time"

 	"github.com/Sirupsen/logrus"

@@ -523,10 +522,7 @@ func (b *Builder) run(cID string) (err error) {

 	}()

 	finished := make(chan struct{})

-	var once sync.Once

-	finish := func() { close(finished) }

 	cancelErrCh := make(chan error, 1)

-	defer once.Do(finish)

 	go func() {

 		select {

 		case <-b.clientCtx.Done():

@@ -540,22 +536,37 @@ func (b *Builder) run(cID string) (err error) {

 	}()

 	if err := b.docker.ContainerStart(cID, nil, true, ""); err != nil {

+		close(finished)

+		if cancelErr := <-cancelErrCh; cancelErr != nil {

+			logrus.Debugf("Build cancelled (%v) and got an error from ContainerStart: %v",

+				cancelErr, err)

+		}

 		return err

 	}

 	// Block on reading output from container, stop on err or chan closed

 	if err := <-errCh; err != nil {

+		close(finished)

+		if cancelErr := <-cancelErrCh; cancelErr != nil {

+			logrus.Debugf("Build cancelled (%v) and got an error from errCh: %v",

+				cancelErr, err)

+		}

 		return err

 	}

 	if ret, _ := b.docker.ContainerWait(cID, -1); ret != 0 {

+		close(finished)

+		if cancelErr := <-cancelErrCh; cancelErr != nil {

+			logrus.Debugf("Build cancelled (%v) and got a non-zero code from ContainerWait: %d",

+				cancelErr, ret)

+		}

 		// TODO: change error type, because jsonmessage.JSONError assumes HTTP

 		return &jsonmessage.JSONError{

 			Message: fmt.Sprintf("The command '%s' returned a non-zero code: %d", strings.Join(b.runConfig.Cmd, " "), ret),

 			Code:    ret,

 		}

 	}

-	once.Do(finish)

+	close(finished)

 	return <-cancelErrCh

 }