diff --git a/api/client/build.go b/api/client/build.go
index e6a4749d39..f7f9c5b1fc 100644
--- a/api/client/build.go
+++ b/api/client/build.go
@@ -17,6 +17,7 @@ import (
 	"golang.org/x/net/context"
 
 	"github.com/docker/docker/api"
+	"github.com/docker/docker/builder"
 	"github.com/docker/docker/builder/dockerignore"
 	Cli "github.com/docker/docker/cli"
 	"github.com/docker/docker/opts"
@@ -143,7 +144,7 @@ func (cli *DockerCli) CmdBuild(args ...string) error {
 			}
 		}
 
-		if err := validateContextDirectory(contextDir, excludes); err != nil {
+		if err := builder.ValidateContextDirectory(contextDir, excludes); err != nil {
 			return fmt.Errorf("Error checking context: '%s'.", err)
 		}
 
@@ -281,54 +282,6 @@ func (cli *DockerCli) CmdBuild(args ...string) error {
 	return nil
 }
 
-// validateContextDirectory checks if all the contents of the directory
-// can be read and returns an error if some files can't be read
-// symlinks which point to non-existing files don't trigger an error
-func validateContextDirectory(srcPath string, excludes []string) error {
-	contextRoot, err := getContextRoot(srcPath)
-	if err != nil {
-		return err
-	}
-	return filepath.Walk(contextRoot, func(filePath string, f os.FileInfo, err error) error {
-		// skip this directory/file if it's not in the path, it won't get added to the context
-		if relFilePath, err := filepath.Rel(contextRoot, filePath); err != nil {
-			return err
-		} else if skip, err := fileutils.Matches(relFilePath, excludes); err != nil {
-			return err
-		} else if skip {
-			if f.IsDir() {
-				return filepath.SkipDir
-			}
-			return nil
-		}
-
-		if err != nil {
-			if os.IsPermission(err) {
-				return fmt.Errorf("can't stat '%s'", filePath)
-			}
-			if os.IsNotExist(err) {
-				return nil
-			}
-			return err
-		}
-
-		// skip checking if symlinks point to non-existing files, such symlinks can be useful
-		// also skip named pipes, because they hanging on open
-		if f.Mode()&(os.ModeSymlink|os.ModeNamedPipe) != 0 {
-			return nil
-		}
-
-		if !f.IsDir() {
-			currentFile, err := os.Open(filePath)
-			if err != nil && os.IsPermission(err) {
-				return fmt.Errorf("no permission to read from '%s'", filePath)
-			}
-			currentFile.Close()
-		}
-		return nil
-	})
-}
-
 // validateTag checks if the given image name can be resolved.
 func validateTag(rawRepo string) (string, error) {
 	_, err := reference.ParseNamed(rawRepo)
diff --git a/builder/context.go b/builder/context.go
new file mode 100644
index 0000000000..61ee97a8ad
--- /dev/null
+++ b/builder/context.go
@@ -0,0 +1,57 @@
+package builder
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/docker/docker/pkg/fileutils"
+)
+
+// ValidateContextDirectory checks if all the contents of the directory
+// can be read and returns an error if some files can't be read
+// symlinks which point to non-existing files don't trigger an error
+func ValidateContextDirectory(srcPath string, excludes []string) error {
+	contextRoot, err := getContextRoot(srcPath)
+	if err != nil {
+		return err
+	}
+	return filepath.Walk(contextRoot, func(filePath string, f os.FileInfo, err error) error {
+		// skip this directory/file if it's not in the path, it won't get added to the context
+		if relFilePath, err := filepath.Rel(contextRoot, filePath); err != nil {
+			return err
+		} else if skip, err := fileutils.Matches(relFilePath, excludes); err != nil {
+			return err
+		} else if skip {
+			if f.IsDir() {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+
+		if err != nil {
+			if os.IsPermission(err) {
+				return fmt.Errorf("can't stat '%s'", filePath)
+			}
+			if os.IsNotExist(err) {
+				return nil
+			}
+			return err
+		}
+
+		// skip checking if symlinks point to non-existing files, such symlinks can be useful
+		// also skip named pipes, because they hanging on open
+		if f.Mode()&(os.ModeSymlink|os.ModeNamedPipe) != 0 {
+			return nil
+		}
+
+		if !f.IsDir() {
+			currentFile, err := os.Open(filePath)
+			if err != nil && os.IsPermission(err) {
+				return fmt.Errorf("no permission to read from '%s'", filePath)
+			}
+			currentFile.Close()
+		}
+		return nil
+	})
+}
diff --git a/api/client/utils_unix.go b/builder/context_unix.go
similarity index 90%
rename from api/client/utils_unix.go
rename to builder/context_unix.go
index ff10ddde9e..d1f72e0573 100644
--- a/api/client/utils_unix.go
+++ b/builder/context_unix.go
@@ -1,6 +1,6 @@
 // +build !windows
 
-package client
+package builder
 
 import (
 	"path/filepath"
diff --git a/api/client/utils_windows.go b/builder/context_windows.go
similarity index 94%
rename from api/client/utils_windows.go
rename to builder/context_windows.go
index 09c33dadd8..b8ba2ba231 100644
--- a/api/client/utils_windows.go
+++ b/builder/context_windows.go
@@ -1,6 +1,6 @@
 // +build windows
 
-package client
+package builder
 
 import (
 	"path/filepath"