diff --git a/lib/eval/dart/bridge/m_provider.dart b/lib/eval/dart/bridge/m_provider.dart
index 9ffed37b..c63265ca 100644
--- a/lib/eval/dart/bridge/m_provider.dart
+++ b/lib/eval/dart/bridge/m_provider.dart
@@ -365,9 +365,10 @@ class MProviderBridged {
           .then((res) {
             if (res.statusCode == 200) {
               final data = jsonDecode(res.body) as Map<String, dynamic>;
-              return data['result'] as bool;
+              // Preserve payloads returned by extension WebView scripts.
+              return data['result'];
             }
-            return false;
+            return null;
           }),
     );
     interpreter.registertopLevelFunction('print', (
diff --git a/lib/eval/javascript/utils.dart b/lib/eval/javascript/utils.dart
index a9782528..261fef36 100644
--- a/lib/eval/javascript/utils.dart
+++ b/lib/eval/javascript/utils.dart
@@ -70,9 +70,11 @@ class JsUtils {
           .then((res) {
             if (res.statusCode == 200) {
               final data = jsonDecode(res.body) as Map<String, dynamic>;
-              return data['result'] as bool;
+              // Extension scripts use this bridge to return extracted values,
+              // not only Cloudflare challenge status.
+              return data['result'];
             }
-            return false;
+            return null;
           });
     });
     runtime.onMessage('parseEpub', (dynamic args) async {