diff --git a/crates/doc/src/vector_regions.rs b/crates/doc/src/vector_regions.rs
index 1d1cd794..b1739160 100644
--- a/crates/doc/src/vector_regions.rs
+++ b/crates/doc/src/vector_regions.rs
@@ -102,10 +102,18 @@ impl VectorNetwork {
         (0..self.regions.len()).rev().find(|r| self.region_contains(*r, p))
     }
 
-    /// Every point on region `r`'s loops (holes' too), each once, sorted.
+    /// Every point on region `r`'s loops (holes' too), each once, sorted (segments or points that
+    /// don't exist are left out).
     pub fn region_points(&self, r: usize) -> Vec<usize> {
         let Some(region) = self.regions.get(r) else { return Vec::new() };
-        let mut out: Vec<usize> = region.loops.iter().flatten().filter_map(|i| self.segments.get(*i)).flat_map(|s| [s.a, s.b]).collect();
+        let mut out: Vec<usize> = region
+            .loops
+            .iter()
+            .flatten()
+            .filter_map(|i| self.segments.get(*i))
+            .flat_map(|s| [s.a, s.b])
+            .filter(|v| *v < self.vertices.len())
+            .collect();
         out.sort_unstable();
         out.dedup();
         out
diff --git a/crates/doc/src/vector_regions_tests.rs b/crates/doc/src/vector_regions_tests.rs
index d1e3d0d8..c3e71163 100644
--- a/crates/doc/src/vector_regions_tests.rs
+++ b/crates/doc/src/vector_regions_tests.rs
@@ -186,6 +186,19 @@ fn empty_and_damaged_networks_have_no_regions_and_never_panic() {
     }
 }
 
+#[test]
+fn region_points_leave_out_segment_ends_that_do_not_exist() {
+    let mut n = VectorNetwork::default();
+    let ring = square(&mut n, 0.0, 0.0, 100.0);
+    n.regions = vec![region(vec![ring], WindingRule::NonZero)];
+    assert_eq!(n.region_points(0), vec![0, 1, 2, 3]);
+    n.segments[3] = Segment::line(3, 9);
+    assert_eq!(n.region_points(0), vec![0, 1, 2, 3]);
+    assert!(n.region_path(0).is_some());
+    n.regions = vec![region(vec![vec![99]], WindingRule::NonZero)];
+    assert!(n.region_points(0).is_empty());
+}
+
 #[test]
 fn the_topology_key_ignores_moved_points_but_not_new_segments() {
     let mut n = nested();