diff --git a/unstable/difft/difft.go b/unstable/difft/difft.go
index ba018e26c..28a6a29a4 100644
--- a/unstable/difft/difft.go
+++ b/unstable/difft/difft.go
@@ -79,14 +79,13 @@ func (edits Edits[T]) apply(xs []T, equals func(T, T) bool) ([]T, error) {
 	return output, nil
 }
 
-type DiffTOptions[T any] struct {
+type DiffOptions[T any] struct {
 	Equals func(T, T) bool
 }
 
-func DiffT[T any](xs, ys []T, opts DiffTOptions[T]) Edits[T] {
-	eq := opts.Equals
-	if eq == nil {
-		eq = func(x T, y T) bool {
+func DiffT[T any](xs, ys []T, opts DiffOptions[T]) Edits[T] {
+	if opts.Equals == nil {
+		opts.Equals = func(x T, y T) bool {
 			return any(x) == any(y)
 		}
 	}
diff --git a/unstable/difft/difft_test.go b/unstable/difft/difft_test.go
index c7d38d085..80aef22c6 100644
--- a/unstable/difft/difft_test.go
+++ b/unstable/difft/difft_test.go
@@ -22,6 +22,7 @@ import (
 )
 
 func TestDiffAppliesCorrectly(t *testing.T) {
+	t.Parallel()
 	rapid.Check(t, func(t *rapid.T) {
 		s1 := rapid.StringMatching(`^[abc]{0,5}`).Draw(t, "s1")
 		s2 := rapid.StringMatching(`^[abc]{0,5}`).Draw(t, "s2")
@@ -29,7 +30,7 @@ func TestDiffAppliesCorrectly(t *testing.T) {
 		eq := func(b1, b2 byte) bool {
 			return b1 == b2
 		}
-		edits := DiffT([]byte(s1), []byte(s2), DiffTOptions[byte]{
+		edits := DiffT([]byte(s1), []byte(s2), DiffOptions[byte]{
 			Equals: eq,
 		})
 
@@ -50,11 +51,12 @@ func TestDiffAppliesCorrectly(t *testing.T) {
 }
 
 func TestDiff(t *testing.T) {
+	t.Parallel()
 	eq := func(a, b byte) bool {
 		return a == b
 	}
 	input := []byte(`mario`)
-	dd := DiffT(input, []byte(`darius`), DiffTOptions[byte]{Equals: eq})
+	dd := DiffT(input, []byte(`darius`), DiffOptions[byte]{Equals: eq})
 	assert.Equal(t, Remove, dd[0].Change)
 	assert.Equal(t, Insert, dd[1].Change)
 	assert.Equal(t, Keep, dd[2].Change)
diff --git a/unstable/difft/matrix_test.go b/unstable/difft/matrix_test.go
index a0a681a3b..138050266 100644
--- a/unstable/difft/matrix_test.go
+++ b/unstable/difft/matrix_test.go
@@ -21,6 +21,7 @@ import (
 )
 
 func TestMatrix(t *testing.T) {
+	t.Parallel()
 	m := newMatrix(3, 3)
 	m.set(1, 1, 42)
 	assert.Equal(t, 42, m.get(1, 1))