diff --git a/filemutex_test.go b/filemutex_test.go
index 43cd6fa..585da1e 100644
--- a/filemutex_test.go
+++ b/filemutex_test.go
@@ -73,6 +73,18 @@ func TestClose(t *testing.T) {
 	m.Close()
 }
 
+func TestOnlyClose(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	path := filepath.Join(dir, "x")
+	m, err := New(path)
+	require.NoError(t, err)
+
+	require.NoError(t, m.Close())
+}
+
 func TestLockErrorsAreRecoverable(t *testing.T) {
 	dir, err := ioutil.TempDir("", "")
 	require.NoError(t, err)
diff --git a/filemutex_windows.go b/filemutex_windows.go
index 3b6c6c4..468b9f0 100644
--- a/filemutex_windows.go
+++ b/filemutex_windows.go
@@ -4,7 +4,14 @@
 
 package filemutex
 
-import "golang.org/x/sys/windows"
+import (
+	"syscall"
+
+	"golang.org/x/sys/windows"
+)
+
+// see https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
+var errLockUnlocked syscall.Errno = 0x9E
 
 // FileMutex is similar to sync.RWMutex, but also synchronizes across processes.
 // This implementation is based on flock syscall.
@@ -51,7 +58,7 @@ func (m *FileMutex) RUnlock() error {
 
 // Close unlocks the lock and closes the underlying file descriptor.
 func (m *FileMutex) Close() error {
-	if err := windows.UnlockFileEx(m.fd, 0, 1, 0, &windows.Overlapped{}); err != nil {
+	if err := windows.UnlockFileEx(m.fd, 0, 1, 0, &windows.Overlapped{}); err != nil && err != errLockUnlocked {
 		return err
 	}
 	return windows.Close(m.fd)