diff --git a/crates/engine/src/tests_disk_cache.rs b/crates/engine/src/tests_disk_cache.rs
index 9c4daa954..fc136c06e 100644
--- a/crates/engine/src/tests_disk_cache.rs
+++ b/crates/engine/src/tests_disk_cache.rs
@@ -156,3 +156,42 @@ fn markers_keep_the_content_key_unless_an_expression_reads_them() {
     s.execute("comp.addMarker", json!({"time": 1.0})).unwrap();
     assert_ne!(key(&s), k1, "a marker read by an expression");
 }
+
+/// A comp marker alone (no layer marker beside it) keeps the key too.
+#[test]
+fn a_lone_comp_marker_keeps_the_content_key() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "M", "width": 8, "height": 8, "frameRate": 30, "duration": 2})).unwrap();
+    let cid = s.active_comp_id().unwrap();
+    s.execute("layer.newSolid", json!({"color": "#ff0000"})).unwrap();
+    let key = |s: &Session| effectcraft_render::disk_cache::comp_content_key(&s.project, cid);
+    let k0 = key(&s);
+    s.execute("comp.addMarker", json!({"time": 0.5, "comment": "beat"})).unwrap();
+    assert_eq!(key(&s), k0);
+}
+
+/// A protected marker with a duration retimes a stretched precomp layer (Responsive Design), so
+/// changing it changes the key of the comp that nests it; a plain marker beside it does not.
+#[test]
+fn protected_markers_with_a_duration_change_the_content_key() {
+    let mut s = Session::default();
+    s.execute("comp.new", json!({"name": "Inner", "width": 8, "height": 8, "frameRate": 30, "duration": 4})).unwrap();
+    let inner = s.active_comp_id().unwrap();
+    s.execute("layer.newSolid", json!({"color": "#ff0000"})).unwrap();
+    s.execute("comp.new", json!({"name": "Outer", "width": 8, "height": 8, "frameRate": 30, "duration": 10})).unwrap();
+    let outer = s.active_comp_id().unwrap();
+    let l = s.execute("layer.addItem", json!({"item": inner.0})).unwrap()["layer"].as_u64().unwrap();
+    s.execute("layer.select", json!({"layers": [l]})).unwrap();
+    s.execute("layer.timeStretch", json!({"percent": 200})).unwrap();
+    let key = |s: &Session| effectcraft_render::disk_cache::comp_content_key(&s.project, outer);
+    let k0 = key(&s);
+    s.execute("comp.addMarker", json!({"comp": inner.0, "time": 2.0, "comment": "beat"})).unwrap();
+    assert_eq!(key(&s), k0, "a plain marker");
+    s.execute("comp.addMarker", json!({"comp": inner.0, "time": 1.0})).unwrap();
+    let index = s.project.comp(inner).unwrap().markers.iter().position(|m| m.time.seconds() == 1.0).unwrap();
+    s.execute("markers.set", json!({"comp": inner.0, "index": index, "duration": 1.0, "protected": true})).unwrap();
+    let k1 = key(&s);
+    assert_ne!(k1, k0, "a protected marker with a duration");
+    s.execute("markers.set", json!({"comp": inner.0, "index": index, "duration": 2.0})).unwrap();
+    assert_ne!(key(&s), k1, "its duration");
+}
diff --git a/crates/project/src/lib.rs b/crates/project/src/lib.rs
index 9ab402d9d..4f6964740 100644
--- a/crates/project/src/lib.rs
+++ b/crates/project/src/lib.rs
@@ -931,7 +931,7 @@ impl Comp {
         if !self.hide_shy
             && self.resolution.is_auto()
             && self.layers.iter().all(|l| l.switches == l.switches.pixels())
-            && (with_markers || (self.markers.iter().all(|m| !is_timing_marker(m)) && self.layers.iter().all(|l| l.markers.is_empty())))
+            && (with_markers || (self.markers.iter().all(is_timing_marker) && self.layers.iter().all(|l| l.markers.is_empty())))
         {
             return std::borrow::Cow::Borrowed(self);
         }