diff --git a/crates/engine/src/cmd/constraints.rs b/crates/engine/src/cmd/constraints.rs
index 1873818c..9be42584 100644
--- a/crates/engine/src/cmd/constraints.rs
+++ b/crates/engine/src/cmd/constraints.rs
@@ -783,7 +783,7 @@ fn run_autoconstrain(s: &mut Session, p: &Value) -> Result<Value> {
     o.distance_tolerance = f64_or(p, "tolerance", o.distance_tolerance);
     o.angle_tolerance = f64_or(p, "angleTolerance", o.angle_tolerance);
     if let Some(t) = p.get("types").and_then(Value::as_array) {
-        o.types = t.iter().filter_map(Value::as_str).map(str::to_string).collect();
+        o.types = t.iter().filter_map(Value::as_str).map(|n| kind_from_name(n).map_or_else(|| n.to_string(), |k| k.name().to_string())).collect();
     }
     let mut d = s.doc()?.clone();
     let ids = cs::autoconstrain(&mut d, &hs, &o);
@@ -922,7 +922,7 @@ fn run_constraintsettings(s: &mut Session, p: &Value) -> Result<Value> {
         set.bar_transparency = t.clamp(0.0, 90.0) as u8;
     }
     if let Some(t) = p.get("autoTypes").and_then(Value::as_array) {
-        set.auto_types = t.iter().filter_map(Value::as_str).filter(|n| kind_from_name(n).is_some()).map(str::to_string).take(32).collect();
+        set.auto_types = t.iter().filter_map(Value::as_str).filter_map(|n| kind_from_name(n).map(|k| k.name().to_string())).take(32).collect();
     }
     if set != cur {
         s.doc_mut()?.parametric.settings = set.clone();
diff --git a/crates/engine/src/cmd/constraints_tests.rs b/crates/engine/src/cmd/constraints_tests.rs
index a07deb54..6bb547e2 100644
--- a/crates/engine/src/cmd/constraints_tests.rs
+++ b/crates/engine/src/cmd/constraints_tests.rs
@@ -142,6 +142,27 @@ fn bars_settings_and_autoconstrain_json() {
     assert_eq!(s.doc().unwrap().constraints[0].kind, ConstraintKind::Horizontal);
 }
 
+#[test]
+fn auto_types_spellings_are_stored_canonically() {
+    for spelling in ["gcParallel", " Parallel ", "parallel"] {
+        let mut s = Session::new();
+        let a = line(&mut s, [0.0, 0.0], [10.0, 10.0]);
+        let b = line(&mut s, [0.0, 3.0], [10.0, 13.01]);
+        let r = s.execute("constraintsettings", &json!({ "autoTypes": [spelling], "angleTolerance": 1 })).unwrap();
+        assert_eq!(r["autoTypes"], json!(["Parallel"]));
+        let r = s.execute("autoconstrain", &json!({ "handles": [a, b] })).unwrap();
+        assert_eq!(r["added"], 1, "{spelling}");
+        assert_eq!(s.doc().unwrap().constraints[0].kind, ConstraintKind::Parallel);
+        // The per-command `types` override accepts the same spellings.
+        let mut s = Session::new();
+        let a = line(&mut s, [0.0, 0.0], [10.0, 10.0]);
+        let b = line(&mut s, [0.0, 3.0], [10.0, 13.01]);
+        let r = s.execute("autoconstrain", &json!({ "handles": [a, b], "types": [spelling], "angleTolerance": 1 })).unwrap();
+        assert_eq!(r["added"], 1, "{spelling}");
+        assert_eq!(s.doc().unwrap().constraints[0].kind, ConstraintKind::Parallel);
+    }
+}
+
 #[test]
 fn hostile_constraint_params_never_panic() {
     let mut s = Session::new();