diff --git a/spec/test-utils/beacon.ts b/spec/test-utils/beacon.ts
index 08771379af1..6cafd337898 100644
--- a/spec/test-utils/beacon.ts
+++ b/spec/test-utils/beacon.ts
@@ -101,26 +101,17 @@ export const makeGeolocationPosition = ({
 }: {
     timestamp?: number;
     coords: Partial<GeolocationCoordinates>;
-}): GeolocationPosition => {
-    const { toJSON, ...coordsJSON } = {
-        accuracy: 1,
-        latitude: 54.001927,
-        longitude: -8.253491,
-        altitude: null,
-        altitudeAccuracy: null,
-        heading: null,
-        speed: null,
-        ...coords,
-    };
-    const posJSON = {
+}): GeolocationPosition =>
+    ({
         timestamp: timestamp ?? 1647256791840,
         coords: {
-            toJSON: () => coordsJSON,
-            ...coordsJSON,
+            accuracy: 1,
+            latitude: 54.001927,
+            longitude: -8.253491,
+            altitude: null,
+            altitudeAccuracy: null,
+            heading: null,
+            speed: null,
+            ...coords,
         },
-    };
-    return {
-        toJSON: () => posJSON,
-        ...posJSON,
-    };
-};
+    }) as GeolocationPosition;
diff --git a/spec/test-utils/webrtc.ts b/spec/test-utils/webrtc.ts
index 519701bdaa9..da3bc2ec0b6 100644
--- a/spec/test-utils/webrtc.ts
+++ b/spec/test-utils/webrtc.ts
@@ -147,13 +147,15 @@ export class MockRTCPeerConnection {
     }
 
     constructor() {
-        const localDescriptionJSON = {
-            sdp: DUMMY_SDP,
-            type: "offer" as RTCSdpType,
-        };
         this.localDescription = {
-            toJSON: () => localDescriptionJSON,
-            ...localDescriptionJSON,
+            sdp: DUMMY_SDP,
+            type: "offer",
+            toJSON: function (): RTCSessionDescriptionInit {
+                return {
+                    sdp: DUMMY_SDP,
+                    type: "offer",
+                };
+            },
         };
 
         this.readyToNegotiate = new Promise<void>((resolve) => {