diff --git a/tfexec/force_unlock.go b/tfexec/force_unlock.go
index e501baf5..de95f547 100644
--- a/tfexec/force_unlock.go
+++ b/tfexec/force_unlock.go
@@ -2,6 +2,7 @@ package tfexec
 
 import (
 	"context"
+	"fmt"
 	"os/exec"
 )
 
@@ -21,7 +22,10 @@ func (opt *DirOption) configureForceUnlock(conf *forceUnlockConfig) {
 
 // ForceUnlock represents the `terraform force-unlock` command
 func (tf *Terraform) ForceUnlock(ctx context.Context, lockID string, opts ...ForceUnlockOption) error {
-	unlockCmd := tf.forceUnlockCmd(ctx, lockID, opts...)
+	unlockCmd, err := tf.forceUnlockCmd(ctx, lockID, opts...)
+	if err != nil {
+		return err
+	}
 
 	if err := tf.runTerraformCmd(ctx, unlockCmd); err != nil {
 		return err
@@ -30,7 +34,7 @@ func (tf *Terraform) ForceUnlock(ctx context.Context, lockID string, opts ...For
 	return nil
 }
 
-func (tf *Terraform) forceUnlockCmd(ctx context.Context, lockID string, opts ...ForceUnlockOption) *exec.Cmd {
+func (tf *Terraform) forceUnlockCmd(ctx context.Context, lockID string, opts ...ForceUnlockOption) (*exec.Cmd, error) {
 	c := defaultForceUnlockOptions
 
 	for _, o := range opts {
@@ -43,8 +47,12 @@ func (tf *Terraform) forceUnlockCmd(ctx context.Context, lockID string, opts ...
 
 	// optional positional arguments
 	if c.dir != "" {
+		err := tf.compatible(ctx, nil, tf0_15_0)
+		if err != nil {
+			return nil, fmt.Errorf("[DIR] option was removed in Terraform v0.15.0")
+		}
 		args = append(args, c.dir)
 	}
 
-	return tf.buildTerraformCmd(ctx, nil, args...)
+	return tf.buildTerraformCmd(ctx, nil, args...), nil
 }
diff --git a/tfexec/force_unlock_test.go b/tfexec/force_unlock_test.go
index b5dc1778..b817979b 100644
--- a/tfexec/force_unlock_test.go
+++ b/tfexec/force_unlock_test.go
@@ -19,7 +19,10 @@ func TestForceUnlockCmd(t *testing.T) {
 	tf.SetEnv(map[string]string{})
 
 	t.Run("defaults", func(t *testing.T) {
-		forceUnlockCmd := tf.forceUnlockCmd(context.Background(), "12345")
+		forceUnlockCmd, err := tf.forceUnlockCmd(context.Background(), "12345")
+		if err != nil {
+			t.Fatal(err)
+		}
 
 		assertCmd(t, []string{
 			"force-unlock",
@@ -28,14 +31,32 @@ func TestForceUnlockCmd(t *testing.T) {
 			"12345",
 		}, nil, forceUnlockCmd)
 	})
+}
+
+// The optional final positional [DIR] argument is available
+// until v0.15.0.
+func TestForceUnlockCmd_pre015(t *testing.T) {
+	td := t.TempDir()
+
+	tf, err := NewTerraform(td, tfVersion(t, testutil.Latest014))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// empty env, to avoid environ mismatch in testing
+	tf.SetEnv(map[string]string{})
 
 	t.Run("override all defaults", func(t *testing.T) {
-		forceUnlockCmd := tf.forceUnlockCmd(context.Background(), "12345", Dir("mydir"))
+		forceUnlockCmd, err := tf.forceUnlockCmd(context.Background(), "12345", Dir("mydir"))
+		if err != nil {
+			t.Fatal(err)
+		}
 
 		assertCmd(t, []string{
 			"force-unlock",
 			"-no-color",
 			"-force",
+			"12345",
 			"mydir",
 		}, nil, forceUnlockCmd)
 	})