diff --git a/FileLiberator/DownloadDecryptBook.cs b/FileLiberator/DownloadDecryptBook.cs
index a2b961c6..1bfea2a6 100644
--- a/FileLiberator/DownloadDecryptBook.cs
+++ b/FileLiberator/DownloadDecryptBook.cs
@@ -78,7 +78,7 @@ namespace FileLiberator
                     contentLic?.ContentMetadata?.ContentUrl?.OfflineUrl,
                     contentLic?.Voucher?.Key,
                     contentLic?.Voucher?.Iv,
-                    Resources.UserAgent
+                    "Audible/671 CFNetwork/1240.0.4 Darwin/20.6.0"
                     );
 
                 if (Configuration.Instance.AllowLibationFixup)
diff --git a/FileManager/BackgroundFileSystem.cs b/FileManager/BackgroundFileSystem.cs
index 91e47916..a239581c 100644
--- a/FileManager/BackgroundFileSystem.cs
+++ b/FileManager/BackgroundFileSystem.cs
@@ -22,6 +22,8 @@ namespace FileManager
 
         public string FindFile(string regexPattern, RegexOptions options)
         {
+            if (fsCache is null) return null;
+
             lock (fsCache)
             {
                 return fsCache.FirstOrDefault(s => Regex.IsMatch(s, regexPattern, options));
diff --git a/LibationLauncher/LibationLauncher.csproj b/LibationLauncher/LibationLauncher.csproj
index acd004f9..c0d121d3 100644
--- a/LibationLauncher/LibationLauncher.csproj
+++ b/LibationLauncher/LibationLauncher.csproj
@@ -13,7 +13,7 @@
     <!-- <PublishSingleFile>true</PublishSingleFile> -->
     <RuntimeIdentifier>win-x64</RuntimeIdentifier>
 
-    <Version>5.4.8.3</Version>
+    <Version>5.4.9.0</Version>
   </PropertyGroup>
 
   <ItemGroup>