diff --git a/crates/engine/src/cmd/array.rs b/crates/engine/src/cmd/array.rs
index 255555a28..da96ccfed 100644
--- a/crates/engine/src/cmd/array.rs
+++ b/crates/engine/src/cmd/array.rs
@@ -374,10 +374,14 @@ fn run_arraypolar(s: &mut Session, p: &Value) -> Result<Value> {
     check_size(s, n.saturating_mul(rows).saturating_mul(levels), hs.len())?;
     let base = point_param(p, "base").or_else(|| s.doc().ok().and_then(|d| first_center(d, &hs))).unwrap_or(c);
     let row_spacing = f64_or(p, "rowSpacing", 1.0);
+    let fill = f64_or(p, "angle", 360.0);
+    if !(fill.abs() >= 1e-9 && fill.abs() <= 360.0 + 1e-9) {
+        return Err(other("Requires a fill angle between -360 and 360 degrees (not 0)."));
+    }
     let kind = ArrayKind::Polar(PolarArray {
         center: c - base,
         items: count32(n),
-        fill: f64_or(p, "angle", 360.0),
+        fill: fill.clamp(-360.0, 360.0),
         rotate: bool_or(p, "rotate", true),
         rows: count32(rows),
         row_spacing,
diff --git a/crates/engine/tests/it/array_commands.rs b/crates/engine/tests/it/array_commands.rs
index d420c36d6..61d5a0d02 100644
--- a/crates/engine/tests/it/array_commands.rs
+++ b/crates/engine/tests/it/array_commands.rs
@@ -212,3 +212,20 @@ fn arrays_over_maxarray_are_refused_not_shrunk() {
     assert!(s.current_prompt().is_none(), "{}", prompt(&s));
     assert_eq!(circle_centers(&s).len(), 2000);
 }
+
+#[test]
+fn json_arraypolar_rejects_bad_fill_angles() {
+    let mut s = Session::new();
+    let h = s.execute("circle", &json!({"center": [5, 0], "radius": 1})).unwrap()["handle"].clone();
+    let before = s.doc().unwrap().model.iter().count();
+    for bad in [0.0, 720.0, -400.0, 360.5] {
+        let p = json!({"handles": [h], "center": [0, 0], "count": 4, "angle": bad, "associative": false});
+        let e = s.execute("arraypolar", &p).unwrap_err();
+        assert!(e.to_string().contains("Requires a fill angle between -360 and 360 degrees"), "{bad}: {e}");
+        assert_eq!(s.doc().unwrap().model.iter().count(), before, "{bad}");
+    }
+    for ok in [360.0, -360.0] {
+        let p = json!({"handles": [h], "center": [0, 0], "count": 4, "angle": ok, "associative": false});
+        s.execute("arraypolar", &p).unwrap();
+    }
+}