diff --git a/crates/script/src/tests.rs b/crates/script/src/tests.rs
index 1bb81887..6f87f757 100644
--- a/crates/script/src/tests.rs
+++ b/crates/script/src/tests.rs
@@ -1385,6 +1385,50 @@ fn key_interpolation_and_ease_apply_outside_the_active_comp() {
     assert!(v[3].as_f64().is_some_and(|x| (x - -44.5).abs() > 1.0), "{v}");
 }
 
+/// #1531: a key the user selected in the property's comp stays selected, and only the named key
+/// changes (on the old code the change went to the selected key instead).
+/// The active comp's own key selection is untouched.
+#[test]
+fn a_per_key_method_in_another_comp_changes_only_its_key_and_keeps_both_selections() {
+    let mut s = session();
+    let o = ok(
+        &mut s,
+        r#"
+        var C = app.project.items.addComp('C', 100, 100, 1, 10, 20);
+        var p = C.layers.addNull().transform.rotation;
+        p.setValuesAtTimes([0, 1, 2], [0, 90, 180]);
+        var A = app.project.items.addComp('A', 100, 100, 1, 10, 20);
+        A.openInViewer();
+        var q = A.layers.addNull().transform.opacity;
+        q.setValuesAtTimes([0, 1], [0, 100]);
+        app.run('edit.deselectAll', {});
+        q.setSelectedAtKey(2, true);
+        // the user selected key 3 of C earlier: C remembers it while A is active
+        p.setSelectedAtKey(3, true);
+        p.setInterpolationTypeAtKey(1, KeyframeInterpolationType.HOLD);
+        p.setTemporalEaseAtKey(2, [new KeyframeEase(0, 80)]);
+        var hold = KeyframeInterpolationType.HOLD;
+        var out = [p.keyOutInterpolationType(1) == hold, p.keyOutInterpolationType(3) == hold, p.keyInInterpolationType(3) == hold,
+          p.keyInTemporalEase(2)[0].influence, p.keyInTemporalEase(3)[0].influence,
+          q.keySelected(1), q.keySelected(2)];
+        p.removeKey(1);
+        out.push(p.numKeys, p.keyTime(1), p.keyValue(1), q.keySelected(2), app.project.activeItem.name);
+        // C's remembered selection is live again once C is active: still the user's key (now 2)
+        C.openInViewer();
+        out.push(p.keySelected(1), p.keySelected(2));
+        out;
+        "#,
+    );
+    let v = o.result.as_array().unwrap();
+    let ease = |i: usize| v[i].as_f64().unwrap();
+    assert_eq!(&v[..3], &[json!(true), json!(false), json!(false)], "only key 1 holds: {v:?}");
+    assert!((ease(3) - 80.0).abs() < 1e-6, "key 2 eased: {v:?}");
+    assert!((ease(4) - 80.0).abs() > 1e-6, "key 3 untouched: {v:?}");
+    assert_eq!(&v[5..7], &[json!(false), json!(true)], "A's key selection kept: {v:?}");
+    assert_eq!(&v[7..12], &[json!(2), json!(1), json!(90), json!(true), json!("A")], "key 1 removed, A still active: {v:?}");
+    assert_eq!(&v[12..], &[json!(false), json!(true)], "C's key selection kept, the target key not added: {v:?}");
+}
+
 /// #808: sourcePointToComp and compPointToSource follow the layer's transform.
 #[test]
 fn source_point_conversions_follow_the_layer_transform() {