diff --git a/src/util/protobufUtil.ts b/src/util/protobufUtil.ts
new file mode 100644
index 0000000..ba91c79
--- /dev/null
+++ b/src/util/protobufUtil.ts
@@ -0,0 +1,31 @@
+import type protobufjs from "protobufjs/minimal";
+
+/**
+ * The protobuf specification demands type-specific default values such as 0 for
+ * numbers when decoding. That is quite weird for TypeScript code which usually
+ * uses null or undefined for missing values. Let's create an alternative way to
+ * decode without defaults.
+ *
+ * Maybe the following issue will be resolved at some point so we would not need
+ * our own workaround:
+ * https://github.com/protobufjs/protobuf.js/issues/1572
+ */
+
+interface ProtobufMessageType<T> {
+  decode: (reader: protobufjs.Reader | Uint8Array, length?: number) => T;
+  toObject: (
+    message: T,
+    options?: protobufjs.IConversionOptions,
+  ) => Record<string, unknown>;
+}
+
+const decodeWithoutDefaults = <T>(
+  messageType: ProtobufMessageType<T>,
+  payload: Uint8Array,
+): T =>
+  messageType.toObject(messageType.decode(payload), {
+    longs: Number,
+    defaults: false,
+  }) as T;
+
+export default decodeWithoutDefaults;
diff --git a/tests/util/protobufUtil.unit.test.ts b/tests/util/protobufUtil.unit.test.ts
new file mode 100644
index 0000000..5344f11
--- /dev/null
+++ b/tests/util/protobufUtil.unit.test.ts
@@ -0,0 +1,97 @@
+import { hfp } from "../../src/protobuf/hfp";
+import { mqtt } from "../../src/protobuf/mqtt";
+import decodeWithoutDefaults from "../../src/util/protobufUtil";
+
+describe("decodeWithoutDefaults", () => {
+  test("decode HFP message with payload stop 'null'", () => {
+    const hfpData = {
+      SchemaVersion: 1,
+      topic: {
+        SchemaVersion: 1,
+        receivedAt: new Date("2023-10-23T13:42:42.794243Z").getTime(),
+        topicPrefix: "/hfp/",
+        topicVersion: "v2",
+        journeyType: hfp.Topic.JourneyType.journey,
+        temporalType: hfp.Topic.TemporalType.ongoing,
+        eventType: hfp.Topic.EventType.VP,
+        transportMode: hfp.Topic.TransportMode.bus,
+        operatorId: 18,
+        vehicleNumber: 1003,
+        uniqueVehicleId: "18/1003",
+        routeId: "5520",
+        directionId: 2,
+        headsign: "Matinkylä (M)",
+        startTime: "15:56",
+        nextStop: "2323253",
+        geohashLevel: 4,
+        latitude: 60.168,
+        longitude: 24.734,
+      },
+      payload: {
+        SchemaVersion: 1,
+        desi: "520",
+        dir: "2",
+        oper: 6,
+        veh: 1003,
+        tst: "2023-10-23T13:42:42.728Z",
+        tsi: 1698068562,
+        spd: 8.49,
+        hdg: 156,
+        lat: 60.168786,
+        long: 24.734465,
+        acc: -1.29,
+        dl: -101,
+        odo: 20729,
+        drst: 0,
+        oday: "2023-10-23",
+        jrn: 812,
+        line: 1110,
+        start: "15:56",
+        loc: hfp.Payload.LocationQualityMethod.GPS,
+        stop: null,
+        route: "5520",
+        occu: 0,
+      },
+    };
+    const verificationErrorMessage = hfp.Data.verify(hfpData);
+    expect(verificationErrorMessage).toBeNull();
+    const encoded = hfp.Data.encode(hfp.Data.create(hfpData)).finish();
+    const withDefaults = hfp.Data.decode(encoded);
+    const noDefaults = decodeWithoutDefaults(hfp.Data, encoded);
+    expect(withDefaults.payload).toHaveProperty("stop");
+    expect(withDefaults.payload.stop).toBeDefined();
+    expect(withDefaults.payload.stop).toStrictEqual(0);
+    expect(withDefaults.payload.loc).toStrictEqual(expect.any(Number));
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+    expect(noDefaults.payload.stop).toBeUndefined();
+    expect(noDefaults.payload).not.toHaveProperty("stop");
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+    expect(noDefaults.payload.loc).toStrictEqual(expect.any(Number));
+    // Change Longs to Numbers so that toMatchObject succeeds.
+    withDefaults.payload.tsi = Number(withDefaults.payload.tsi);
+    if (withDefaults.topic?.receivedAt != null) {
+      withDefaults.topic.receivedAt = Number(withDefaults.topic.receivedAt);
+    }
+    expect(withDefaults).toMatchObject(noDefaults);
+  });
+
+  test("decode MQTT message with missing topic", () => {
+    const mqttMessage = {
+      SchemaVersion: 1,
+      payload: Buffer.from("foo", "utf8"),
+    };
+    const verificationErrorMessage = mqtt.RawMessage.verify(mqttMessage);
+    expect(verificationErrorMessage).toBeNull();
+    const encoded = mqtt.RawMessage.encode(
+      mqtt.RawMessage.create(mqttMessage),
+    ).finish();
+    const withDefaults = mqtt.RawMessage.decode(encoded);
+    const noDefaults = decodeWithoutDefaults(mqtt.RawMessage, encoded);
+    expect(withDefaults).toHaveProperty("topic");
+    expect(withDefaults.topic).toBeDefined();
+    expect(withDefaults.topic).toStrictEqual("");
+    expect(noDefaults).not.toHaveProperty("topic");
+    expect(noDefaults.topic).toBeUndefined();
+    expect(withDefaults).toMatchObject(noDefaults);
+  });
+});