diff --git a/src/input/triangulation.rs b/src/input/triangulation.rs
index 563def0..3ed72bd 100644
--- a/src/input/triangulation.rs
+++ b/src/input/triangulation.rs
@@ -61,7 +61,11 @@ impl Triangulation {
     /// Epsilon is the minimum area a point should contribute to a polygon.
     #[cfg_attr(feature = "tracing", instrument(skip_all))]
     pub fn simplify(&mut self, epsilon: f32) {
-        self.inner = self.inner.simplify_vw_preserve(&epsilon);
+        self.inner.interiors_mut(|interiors| {
+            for interior in interiors {
+                *interior = interior.simplify_vw_preserve(&epsilon);
+            }
+        });
     }
 
     #[cfg_attr(feature = "tracing", instrument(skip_all))]
diff --git a/tests/triangulation.rs b/tests/triangulation.rs
index 139cb23..6e9838a 100644
--- a/tests/triangulation.rs
+++ b/tests/triangulation.rs
@@ -161,3 +161,79 @@ fn is_in_mesh_overlapping_merged() {
         }
     }
 }
+
+#[test]
+fn is_in_mesh_simplified() {
+    let mut triangulation = Triangulation::from_outer_edges(&[
+        vec2(0.0, 0.0),
+        vec2(10.0, 0.0),
+        vec2(10.0, 10.0),
+        vec2(0.0, 10.0),
+    ]);
+    // adding a circle obstacle in the middle
+    let nb_points = 100;
+    let radius = 2.5;
+    triangulation.add_obstacle(
+        (0..nb_points)
+            .map(|i| {
+                let angle = i as f32 * std::f32::consts::TAU / nb_points as f32;
+                let (x, y) = angle.sin_cos();
+                vec2(x, y) * radius + vec2(5.0, 5.0)
+            })
+            .collect(),
+    );
+    let polygons_before = triangulation.as_navmesh().polygons;
+    triangulation.simplify(0.1);
+    let mesh: Mesh = triangulation.as_navmesh();
+    assert!(dbg!(polygons_before.len()) > dbg!(mesh.polygons.len()));
+    for i in 0..20 {
+        for j in 0..20 {
+            let point = vec2(i as f32 / 2.0, j as f32 / 2.0);
+            if point.distance(vec2(5.0, 5.0)) < radius {
+                assert!(!mesh.point_in_mesh(point));
+            } else {
+                assert!(mesh.point_in_mesh(point));
+            }
+        }
+    }
+}
+
+#[test]
+fn is_in_mesh_overlapping_simplified() {
+    let mut triangulation = Triangulation::from_outer_edges(&[
+        vec2(0.0, 0.0),
+        vec2(10.0, 0.0),
+        vec2(10.0, 10.0),
+        vec2(0.0, 10.0),
+    ]);
+    // adding a circle obstacle in the middle
+    let nb_points = 1000;
+    let radius = 2.5;
+    triangulation.add_obstacle(
+        (0..nb_points)
+            .map(|i| {
+                let angle = i as f32 * std::f32::consts::TAU / nb_points as f32;
+                let (x, y) = angle.sin_cos();
+                vec2(x, y) * radius + vec2(5.0, 5.0)
+            })
+            .collect(),
+    );
+    triangulation.add_obstacle(vec![
+        vec2(2.5, 2.5),
+        vec2(2.5, 5.0),
+        vec2(5.0, 5.0),
+        vec2(5.0, 2.5),
+    ]);
+
+    let mesh_before = triangulation.as_navmesh();
+    triangulation.simplify(0.01);
+    let mesh: Mesh = triangulation.as_navmesh();
+    assert!(dbg!(mesh_before.polygons.len()) > dbg!(mesh.polygons.len()));
+    let resolution = 5;
+    for i in 0..(10 * resolution) {
+        for j in 0..(10 * resolution) {
+            let point = vec2(i as f32 / resolution as f32, j as f32 / resolution as f32);
+            assert_eq!(mesh.point_in_mesh(point), mesh_before.point_in_mesh(point));
+        }
+    }
+}