diff --git a/GameRes/ArcFile.cs b/GameRes/ArcFile.cs
index 7afc2d31..8911d4f3 100644
--- a/GameRes/ArcFile.cs
+++ b/GameRes/ArcFile.cs
@@ -71,48 +71,32 @@ namespace GameRes
         {
             if (entry.Size < 4)
                 return null;
-            var filename = entry.Name;
-            var ext = new Lazy<string> (() => Path.GetExtension (filename).TrimStart ('.').ToLowerInvariant(), false);
             var file = VFS.OpenView (entry);
             try
             {
                 uint signature = file.View.ReadUInt32 (0);
-                var tried = Enumerable.Empty<ArchiveFormat>();
-                for (;;)
+                foreach (var impl in FormatCatalog.Instance.FindFormats<ArchiveFormat> (entry.Name, signature))
                 {
-                    var range = FormatCatalog.Instance.LookupSignature<ArchiveFormat> (signature);
-                    if (tried.Any())
-                        range = range.Except (tried);
-                    // check formats that match filename extension first
-                    if (range.Skip(1).Any()) // if range.Count() > 1
-                        range = range.OrderByDescending (f => f.Extensions.Any (e => e == ext.Value));
-                    foreach (var impl in range)
+                    try
                     {
-                        try
+                        var arc = impl.TryOpen (file);
+                        if (null != arc)
                         {
-                            var arc = impl.TryOpen (file);
-                            if (null != arc)
-                            {
-                                file = null; // file ownership passed to ArcFile
-                                return arc;
-                            }
-                        }
-                        catch (OperationCanceledException X)
-                        {
-                            FormatCatalog.Instance.LastError = X;
-                            return null;
-                        }
-                        catch (Exception X)
-                        {
-                            // ignore failed open attmepts
-                            Trace.WriteLine (string.Format ("[{0}] {1}: {2}", impl.Tag, filename, X.Message));
-                            FormatCatalog.Instance.LastError = X;
+                            file = null; // file ownership passed to ArcFile
+                            return arc;
                         }
                     }
-                    if (0 == signature)
-                        break;
-                    signature = 0;
-                    tried = range;
+                    catch (OperationCanceledException X)
+                    {
+                        FormatCatalog.Instance.LastError = X;
+                        return null;
+                    }
+                    catch (Exception X)
+                    {
+                        // ignore failed open attmepts
+                        Trace.WriteLine (string.Format ("[{0}] {1}: {2}", impl.Tag, entry.Name, X.Message));
+                        FormatCatalog.Instance.LastError = X;
+                    }
                 }
             }
             finally
diff --git a/GameRes/Audio.cs b/GameRes/Audio.cs
index 1e9a0e14..9424b5f2 100644
--- a/GameRes/Audio.cs
+++ b/GameRes/Audio.cs
@@ -171,27 +171,23 @@ namespace GameRes
 
         public static SoundInput Read (IBinaryStream file)
         {
-            uint signature = file.Signature;
-            for (;;)
+            foreach (var impl in FormatCatalog.Instance.FindFormats<AudioFormat> (file.Name, file.Signature))
             {
-                var range = FormatCatalog.Instance.LookupSignature<AudioFormat> (signature);
-                foreach (var impl in range)
+                try
                 {
-                    try
-                    {
-                        file.Position = 0;
-                        SoundInput sound = impl.TryOpen (file);
-                        if (null != sound)
-                            return sound;
-                    }
-                    catch (System.Exception X)
-                    {
-                        FormatCatalog.Instance.LastError = X;
-                    }
+                    file.Position = 0;
+                    SoundInput sound = impl.TryOpen (file);
+                    if (null != sound)
+                        return sound;
+                }
+                catch (OperationCanceledException)
+                {
+                    throw;
+                }
+                catch (System.Exception X)
+                {
+                    FormatCatalog.Instance.LastError = X;
                 }
-                if (0 == signature)
-                    break;
-                signature = 0;
             }
             return null;
         }
diff --git a/GameRes/FormatCatalog.cs b/GameRes/FormatCatalog.cs
index 8e866c64..8c5e1b62 100644
--- a/GameRes/FormatCatalog.cs
+++ b/GameRes/FormatCatalog.cs
@@ -163,6 +163,32 @@ namespace GameRes
             return LookupSignature (signature).OfType<Type>();
         }
 
+        /// <summary>
+        /// Enumerate resources matching specified <paramref name="signature"/> and filename extension.
+        /// </summary>
+        internal IEnumerable<ResourceType> FindFormats<ResourceType> (string filename, uint signature) where ResourceType : IResource
+        {
+            var ext = new Lazy<string> (() => Path.GetExtension (filename).TrimStart ('.').ToLowerInvariant(), false);
+            var tried = Enumerable.Empty<ResourceType>();
+            for (;;)
+            {
+                var range = LookupSignature<ResourceType> (signature);
+                if (tried.Any())
+                    range = range.Except (tried);
+                // check formats that match filename extension first
+                if (range.Skip (1).Any()) // if range.Count() > 1
+                    range = range.OrderByDescending (f => f.Extensions.Any (e => e == ext.Value));
+                foreach (var impl in range)
+                {
+                    yield return impl;
+                }
+                if (0 == signature)
+                    break;
+                signature = 0;
+                tried = range;
+            }
+        }
+
         /// <summary>
         /// Create GameRes.Entry corresponding to <paramref name="filename"/> extension.
         /// <exception cref="System.ArgumentException">May be thrown if filename contains invalid
diff --git a/GameRes/Image.cs b/GameRes/Image.cs
index 6a9e5d73..1773ec93 100644
--- a/GameRes/Image.cs
+++ b/GameRes/Image.cs
@@ -131,37 +131,23 @@ namespace GameRes
 
         public static System.Tuple<ImageFormat, ImageMetaData> FindFormat (IBinaryStream file)
         {
-            uint signature = file.Signature;
-            Lazy<string> ext = null;
-            if (!string.IsNullOrEmpty (file.Name))
-                ext = new Lazy<string> (() => Path.GetExtension (file.Name).TrimStart ('.').ToLowerInvariant(), false);
-            for (;;)
+            foreach (var impl in FormatCatalog.Instance.FindFormats<ImageFormat> (file.Name, file.Signature))
             {
-                var range = FormatCatalog.Instance.LookupSignature<ImageFormat> (signature);
-                // check formats that match filename extension first
-                if (ext != null && range.Skip(1).Any())
-                    range = range.OrderByDescending (f => f.Extensions.Any (e => e == ext.Value));
-                foreach (var impl in range)
+                try
                 {
-                    try
+                    file.Position = 0;
+                    ImageMetaData metadata = impl.ReadMetaData (file);
+                    if (null != metadata)
                     {
-                        file.Position = 0;
-                        ImageMetaData metadata = impl.ReadMetaData (file);
-                        if (null != metadata)
-                        {
-                            metadata.FileName = file.Name;
-                            return Tuple.Create (impl, metadata);
-                        }
+                        metadata.FileName = file.Name;
+                        return Tuple.Create (impl, metadata);
                     }
-                    catch (OperationCanceledException)
-                    {
-                        throw;
-                    }
-                    catch { }
                 }
-                if (0 == signature)
-                    break;
-                signature = 0;
+                catch (OperationCanceledException)
+                {
+                    throw;
+                }
+                catch { }
             }
             return null;
         }