diff --git a/src/store/actions.js b/src/store/actions.js
index 87d68e8..b719aa6 100644
--- a/src/store/actions.js
+++ b/src/store/actions.js
@@ -122,7 +122,8 @@ const getLastLocations = async ({ commit, state }) => {
   commit(types.SET_LAST_LOCATIONS, lastLocations);
 };
 
-const _getTravelStats = (locationHistory) => {
+// Export for testing purposes only 
+export const _getTravelStats = (locationHistory) => {
   const start = Date.now();
   let distanceTravelled = 0;
   let elevationGain = 0;
@@ -130,16 +131,21 @@ const _getTravelStats = (locationHistory) => {
   Object.keys(locationHistory).forEach((user) => {
     Object.keys(locationHistory[user]).forEach((device) => {
       let lastLatLng = null;
+      let lastAlt = null;
       locationHistory[user][device].forEach((location) => {
         if (
           config.filters.minAccuracy !== null &&
           location.acc > config.filters.minAccuracy
         )
           return;
-        const latLng = L.latLng(location.lat, location.lon, location.alt ?? 0);
+        const latLng = L.latLng(location.lat, location.lon, location.alt);
         if (lastLatLng !== null) {
           const distance = distanceBetweenCoordinates(lastLatLng, latLng);
-          const elevationChange = latLng.alt - lastLatLng.alt;
+          // calculate the elevationChange only if there is an alt available
+          let elevationChange = 0;
+          if (lastAlt !== null && latLng.alt !== undefined) {
+            elevationChange = latLng.alt - lastAlt;
+          }
           if (
             typeof config.map.maxPointDistance === "number" &&
             config.map.maxPointDistance > 0
@@ -153,6 +159,9 @@ const _getTravelStats = (locationHistory) => {
             else elevationLoss += -elevationChange;
           }
         }
+        if (latLng.alt !== undefined) {
+          lastAlt = latLng.alt;
+        }
         lastLatLng = latLng;
       });
     });
diff --git a/tests/actions.test.js b/tests/actions.test.js
new file mode 100644
index 0000000..edd8656
--- /dev/null
+++ b/tests/actions.test.js
@@ -0,0 +1,31 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { _getTravelStats } from "@/store/actions";
+
+import { L } from "leaflet";
+
+describe("_getTravelStats", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("calculates total distance and elevation with and without alt", () => {
+    const testData = {
+      user1: {
+        device1: [
+          { lat: 52.214908, lon: 8.116938, alt: 100, acc: 5 },
+          { lat: 52.214908, lon: 8.116938, alt: 105, acc: 5 },
+          { lat: 52.220619, lon: 8.104137, /* no alt */ acc: 5 },
+          { lat: 52.220619, lon: 8.104137, alt: 95, acc: 5 },
+          { lat: 52.227348, lon: 8.094349, /* no alt */ acc: 5 },
+        ],
+      },
+    };
+
+    const stats = _getTravelStats(testData);
+
+    expect(stats.distanceTravelled).toBeCloseTo(2080.9568);
+    expect(stats.elevationGain).toBe(5);
+    expect(stats.elevationLoss).toBe(10);
+  });
+
+});