diff --git a/src/db/rtept.test.ts b/src/db/rtept.test.ts
index 0d91205..d28d982 100644
--- a/src/db/rtept.test.ts
+++ b/src/db/rtept.test.ts
@@ -131,4 +131,59 @@ describe('The rtept module with a real db', () => {
     expect(await getRte({ id: idRte })).toEqual(rte2);
     expect((await get(idRtept)).doc).toEqual(rtept4);
   });
+  it('can write a rtept outside a rte with a negative index', async () => {
+    const idRte = 'gpx/4320836410265485/2rte/000034';
+    const idRtept = 'gpx/4320836410265485/2rte/000034/000035';
+    const rtept3: Wpt = {
+      $: { lat: 3, lon: 3 },
+    };
+    const rtept4: Wpt = {
+      $: { lat: 4, lon: 4 },
+    };
+    const rte0: Rte = {
+      name: 'A new route',
+      rtept: [
+        {
+          $: { lat: 1, lon: 1 },
+        },
+        {
+          $: { lat: 2, lon: 2 },
+        },
+      ],
+    };
+    const rte1: Rte = {
+      name: 'A new route',
+      rtept: [
+        {
+          $: { lat: 1, lon: 1 },
+        },
+        {
+          $: { lat: 2, lon: 2 },
+        },
+        rtept3,
+      ],
+    };
+    const rte2: Rte = {
+      name: 'A new route',
+      rtept: [
+        {
+          $: { lat: 1, lon: 1 },
+        },
+        {
+          $: { lat: 2, lon: 2 },
+        },
+        rtept4,
+      ],
+    };
+
+    const rtePut = await putRte({ id: idRte, rte: rte0 });
+    await put(idRtept, 'rtept', () => rtept3, emptyWpt);
+    await putRtept({
+      idRte,
+      index: -1,
+      rtept: rtept4,
+    });
+    expect(await getRte({ id: idRte })).toEqual(rte2);
+    expect((await get(idRtept)).doc).toEqual(rtept4);
+  });
 });
diff --git a/src/db/rtept.ts b/src/db/rtept.ts
index f1adddb..efb6410 100644
--- a/src/db/rtept.ts
+++ b/src/db/rtept.ts
@@ -32,7 +32,7 @@ export const putRtept = async (params: any) => {
   const nbRteptInRte = rte && rte.rtept ? rte.rtept.length : 0;
   const nbRteptOutRte = docs.rows.length - 1;
   const nbRtept = nbRteptInRte + nbRteptOutRte;
-  const positiveIndex = index >= 0 ? index : nbRtept - index;
+  const positiveIndex = index >= 0 ? index : nbRtept + index;
   // console.log({
   //   caller: 'putRtept',
   //   nbRteptInRte,