diff --git a/src/main.tsx b/src/main.tsx
index 2a64364..50aa6cd 100644
--- a/src/main.tsx
+++ b/src/main.tsx
@@ -36,6 +36,14 @@ initRageshake();
 
 console.info(`matrix-video-chat ${import.meta.env.VITE_APP_VERSION || "dev"}`);
 
+if (!window.isSecureContext) {
+  throw new Error(
+    "This app cannot run in an insecure context. To fix this, access the app " +
+      "via a local loopback address, or serve it over HTTPS.\n" +
+      "https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts"
+  );
+}
+
 if (import.meta.env.VITE_CUSTOM_THEME) {
   const style = document.documentElement.style;
   style.setProperty("--accent", import.meta.env.VITE_THEME_ACCENT as string);
diff --git a/src/room/InCallView.jsx b/src/room/InCallView.jsx
index 4a4c1cb..43a71a8 100644
--- a/src/room/InCallView.jsx
+++ b/src/room/InCallView.jsx
@@ -44,7 +44,7 @@ import { useShowInspector } from "../settings/useSetting";
 import { useModalTriggerState } from "../Modal";
 import { useAudioContext } from "../video-grid/useMediaStream";
 
-const canScreenshare = "getDisplayMedia" in navigator.mediaDevices;
+const canScreenshare = "getDisplayMedia" in (navigator.mediaDevices ?? {});
 // There is currently a bug in Safari our our code with cloning and sending MediaStreams
 // or with getUsermedia and getDisplaymedia being used within the same session.
 // For now we can disable screensharing in Safari.