diff --git a/crates/engine/src/cmd/sketch.rs b/crates/engine/src/cmd/sketch.rs
index 61abb2bb..17fc3339 100644
--- a/crates/engine/src/cmd/sketch.rs
+++ b/crates/engine/src/cmd/sketch.rs
@@ -1738,14 +1738,18 @@ fn construction(s: &mut Session, p: &Value) -> Result<Value> {
         let cs: Vec<usize> =
             ids.iter().map(|id| sk.curve_index(id).ok_or_else(|| bad(cmd, format!("unknown curve `{id}`")))).collect::<Result<_>>()?;
         // The selection switches together (a slot or polygon as a whole): to construction
-        // unless all of it already is. Projected curves may switch too.
+        // unless all of it already is. Projected curves may switch too. A centerline that
+        // becomes construction stops being a centerline (one line type at a time).
         let to = want.unwrap_or_else(|| !cs.iter().all(|c| sk.curves.get(*c).is_some_and(|c| c.construction)));
         let mut n = 0;
         for c in cs {
             if let Some(cu) = sk.curves.get_mut(c)
-                && cu.construction != to
+                && (cu.construction != to || to && cu.centerline)
             {
                 cu.construction = to;
+                if to {
+                    cu.centerline = false;
+                }
                 n += 1;
             }
         }
diff --git a/crates/engine/src/cmd/sketch_ux_tests.rs b/crates/engine/src/cmd/sketch_ux_tests.rs
index f63925a4..007f9ed9 100644
--- a/crates/engine/src/cmd/sketch_ux_tests.rs
+++ b/crates/engine/src/cmd/sketch_ux_tests.rs
@@ -237,6 +237,21 @@ fn construction_toggle_takes_shapes_out_of_profiles_and_back() {
     assert!(s.execute("sketch.construction", &json!({"curves": ["nope"]})).is_err());
 }
 
+#[test]
+fn centerline_can_become_construction_directly() {
+    let mut s = new_sketch();
+    let l = curve_ids(&run(&mut s, "sketch.line", json!({"points": [[0, 0], [20, 0]]})));
+    run(&mut s, "sketch.centerline", json!({ "curves": l, "value": true }));
+    let r = run(&mut s, "sketch.construction", json!({ "curves": l, "value": true }));
+    assert_eq!(r["changed"], 1);
+    let sk = sketch(&s);
+    assert!(sk.curves.iter().filter(|c| l.contains(&c.id)).all(|c| c.construction && !c.centerline));
+    // And back to a centerline.
+    run(&mut s, "sketch.centerline", json!({ "curves": l, "value": true }));
+    let sk = sketch(&s);
+    assert!(sk.curves.iter().filter(|c| l.contains(&c.id)).all(|c| c.centerline && !c.construction));
+}
+
 #[test]
 fn projected_geometry_can_become_construction() {
     let mut s = Session::default();