diff --git a/samples/flushfs/flush_fs.go b/samples/flushfs/flush_fs.go
index b30c8b0..8984972 100644
--- a/samples/flushfs/flush_fs.go
+++ b/samples/flushfs/flush_fs.go
@@ -24,11 +24,14 @@ import (
 	"golang.org/x/net/context"
 )
 
-// Create a file system containing a single file named "foo".
+// Create a file system whose sole contents are a file named "foo" and a
+// directory named "bar".
 //
 // The file may be opened for reading and/or writing. Its initial contents are
 // empty. Whenever a flush or fsync is received, the supplied function will be
 // called with the current contents of the file and its status returned.
+//
+// The directory cannot be modified.
 func NewFileSystem(
 	reportFlush func(string) error,
 	reportFsync func(string) error) (fs fuse.FileSystem, err error) {
@@ -40,7 +43,10 @@ func NewFileSystem(
 	return
 }
 
-const fooID = fuse.RootInodeID + 1
+const (
+	fooID = fuse.RootInodeID + 1 + iota
+	barID
+)
 
 type flushFS struct {
 	fuseutil.NotImplementedFileSystem
@@ -72,6 +78,14 @@ func (fs *flushFS) fooAttributes() fuse.InodeAttributes {
 	}
 }
 
+// LOCKS_REQUIRED(fs.mu)
+func (fs *flushFS) barAttributes() fuse.InodeAttributes {
+	return fuse.InodeAttributes{
+		Nlink: 1,
+		Mode:  0777 | os.ModeDir,
+	}
+}
+
 ////////////////////////////////////////////////////////////////////////
 // File system methods
 ////////////////////////////////////////////////////////////////////////
@@ -94,14 +108,28 @@ func (fs *flushFS) LookUpInode(
 	defer fs.mu.Unlock()
 
 	// Sanity check.
-	if req.Parent != fuse.RootInodeID || req.Name != "foo" {
+	if req.Parent != fuse.RootInodeID {
 		err = fuse.ENOENT
 		return
 	}
 
-	resp.Entry = fuse.ChildInodeEntry{
-		Child:      fooID,
-		Attributes: fs.fooAttributes(),
+	// Set up the entry.
+	switch req.Name {
+	case "foo":
+		resp.Entry = fuse.ChildInodeEntry{
+			Child:      fooID,
+			Attributes: fs.fooAttributes(),
+		}
+
+	case "bar":
+		resp.Entry = fuse.ChildInodeEntry{
+			Child:      barID,
+			Attributes: fs.barAttributes(),
+		}
+
+	default:
+		err = fuse.ENOENT
+		return
 	}
 
 	return
@@ -125,6 +153,10 @@ func (fs *flushFS) GetInodeAttributes(
 		resp.Attributes = fs.fooAttributes()
 		return
 
+	case barID:
+		resp.Attributes = fs.barAttributes()
+		return
+
 	default:
 		err = fuse.ENOENT
 		return
@@ -222,3 +254,21 @@ func (fs *flushFS) FlushFile(
 	err = fs.reportFlush(string(fs.fooContents))
 	return
 }
+
+func (fs *flushFS) OpenDir(
+	ctx context.Context,
+	req *fuse.OpenDirRequest) (
+	resp *fuse.OpenDirResponse, err error) {
+	resp = &fuse.OpenDirResponse{}
+
+	fs.mu.Lock()
+	defer fs.mu.Unlock()
+
+	// Sanity check.
+	if req.Inode != barID {
+		err = fuse.ENOSYS
+		return
+	}
+
+	return
+}
diff --git a/samples/flushfs/flush_fs_test.go b/samples/flushfs/flush_fs_test.go
index a5ffeb2..6ea5423 100644
--- a/samples/flushfs/flush_fs_test.go
+++ b/samples/flushfs/flush_fs_test.go
@@ -614,7 +614,29 @@ func (t *NoErrorsTest) Mmap_CloseBeforeMunmap() {
 }
 
 func (t *NoErrorsTest) Directory() {
-	AssertTrue(false, "TODO")
+	var err error
+
+	// Open the directory.
+	t.f1, err = os.Open(path.Join(t.Dir, "bar"))
+	AssertEq(nil, err)
+
+	// Sanity check: stat it.
+	fi, err := t.f1.Stat()
+	AssertEq(nil, err)
+	AssertEq(0777|os.ModeDir, fi.Mode())
+
+	// Sync it.
+	err = t.f1.Sync()
+	AssertEq(nil, err)
+
+	// Close it.
+	err = t.f1.Close()
+	t.f1 = nil
+	AssertEq(nil, err)
+
+	// No flushes or fsync requests should have been received.
+	ExpectThat(t.getFlushes(), ElementsAre())
+	ExpectThat(t.getFsyncs(), ElementsAre())
 }
 
 ////////////////////////////////////////////////////////////////////////
diff --git a/samples/subprocess.go b/samples/subprocess.go
index 38733bf..2d954b0 100644
--- a/samples/subprocess.go
+++ b/samples/subprocess.go
@@ -236,6 +236,7 @@ func (t *SubprocessTest) initialize() (err error) {
 
 	// Set up basic args for the subprocess.
 	args := []string{
+		"--fuse.debug",
 		"--type",
 		t.MountType,
 		"--mount_point",
@@ -270,7 +271,7 @@ func (t *SubprocessTest) initialize() (err error) {
 	// Set up a command.
 	var stderr bytes.Buffer
 	mountCmd := exec.Command(toolPath, args...)
-	mountCmd.Stderr = &stderr
+	mountCmd.Stderr = os.Stderr
 	mountCmd.ExtraFiles = extraFiles
 
 	// Start it.