diff --git a/src/lib/announce.ts b/src/lib/announce.ts
index 153b82df..c87e27a2 100644
--- a/src/lib/announce.ts
+++ b/src/lib/announce.ts
@@ -18,8 +18,17 @@ export interface AnnounceOptions {
   assertive?: boolean;
 }
 
+function isIos(): boolean {
+  try {
+    return Platform.OS === 'ios';
+  } catch {
+    // A react-native stand-in without Platform (tests).
+    return false;
+  }
+}
+
 export function announce(message: string, options: AnnounceOptions = {}): void {
-  if (Platform.OS !== 'ios') return;
+  if (!isIos()) return;
   const text = message.replace(/\s+/g, ' ').trim();
   if (!text) return;
   const now = Date.now();
diff --git a/src/lib/screen-reader.ts b/src/lib/screen-reader.ts
index f95a59b3..50eee3d1 100644
--- a/src/lib/screen-reader.ts
+++ b/src/lib/screen-reader.ts
@@ -10,8 +10,8 @@ let watching = false;
 function watch(): void {
   if (watching) return;
   watching = true;
-  const info = AccessibilityInfo as typeof AccessibilityInfo | undefined;
   try {
+    const info = AccessibilityInfo as typeof AccessibilityInfo | undefined;
     void info?.isScreenReaderEnabled?.().then((on) => { screenReaderOn = on; }).catch(() => undefined);
     info?.addEventListener?.('screenReaderChanged', (on: boolean) => { screenReaderOn = on; });
   } catch {