diff --git a/src/helpers/recordingValidation.js b/src/helpers/recordingValidation.js
index 503f01366..504e4d6e5 100644
--- a/src/helpers/recordingValidation.js
+++ b/src/helpers/recordingValidation.js
@@ -3,7 +3,9 @@ import { isEmptyRecording } from "./recordingGuard.js";
 // Decide whether a finished MediaRecorder session carries real audio before we
 // hand it to the transcription backend. A fast tap can flush only the container
 // header, or deliver no chunks at all, which crashes FFmpeg. See issue #871.
-export function evaluateFinishedRecording({ blobSize, receivedAudioData } = {}) {
+export function evaluateFinishedRecording(params = {}) {
+  const { blobSize, receivedAudioData } =
+    params && typeof params === "object" ? params : {};
   if (!receivedAudioData) {
     return { usable: false, reason: "no-audio-data" };
   }
diff --git a/test/helpers/recordingValidation.test.js b/test/helpers/recordingValidation.test.js
index 3fc919f86..795db4073 100644
--- a/test/helpers/recordingValidation.test.js
+++ b/test/helpers/recordingValidation.test.js
@@ -43,10 +43,14 @@ test("rejects 255 bytes (just under the threshold)", async () => {
   });
 });
 
-test("treats missing / undefined args as unusable (defensive, does not throw)", async () => {
+test("treats missing / undefined / null args as unusable (defensive, does not throw)", async () => {
   const { evaluateFinishedRecording } = await load();
   assert.deepEqual(evaluateFinishedRecording(), { usable: false, reason: "no-audio-data" });
+  assert.deepEqual(evaluateFinishedRecording(null), { usable: false, reason: "no-audio-data" });
+  assert.deepEqual(evaluateFinishedRecording(undefined), { usable: false, reason: "no-audio-data" });
   assert.deepEqual(evaluateFinishedRecording({}), { usable: false, reason: "no-audio-data" });
+  assert.deepEqual(evaluateFinishedRecording("invalid"), { usable: false, reason: "no-audio-data" });
+  assert.deepEqual(evaluateFinishedRecording(123), { usable: false, reason: "no-audio-data" });
   assert.deepEqual(evaluateFinishedRecording({ receivedAudioData: true }), {
     usable: false,
     reason: "empty-container",