diff --git a/FmiSrl.FtpServer.Server/Abstractions/IFileSystemProvider.cs b/FmiSrl.FtpServer.Server/Abstractions/IFileSystemProvider.cs
index 96baebd..67add4f 100644
--- a/FmiSrl.FtpServer.Server/Abstractions/IFileSystemProvider.cs
+++ b/FmiSrl.FtpServer.Server/Abstractions/IFileSystemProvider.cs
@@ -69,6 +69,14 @@ public interface IFileSystemProvider
     /// <returns>A task that represents the asynchronous operation. The task result contains <c>true</c> if the directory exists; otherwise, <c>false</c>.</returns>
     Task<bool> DirectoryExistsAsync(FtpAuthenticationContext authContext, string path);
 
+    /// <summary>
+    /// Gets a single file system entry for the specified path.
+    /// </summary>
+    /// <param name="authContext">The authentication context for the operation.</param>
+    /// <param name="path">The path to get the entry for.</param>
+    /// <returns>A task that represents the asynchronous operation. The task result contains the <see cref="FileSystemEntry"/> or <c>null</c> if not found.</returns>
+    Task<FileSystemEntry?> GetEntryAsync(FtpAuthenticationContext authContext, string path);
+
     /// <summary>
     /// Renames a file or directory.
     /// </summary>
diff --git a/FmiSrl.FtpServer.Server/Commands/RetrCommand.cs b/FmiSrl.FtpServer.Server/Commands/RetrCommand.cs
index 8535eb4..4ea3b7f 100644
--- a/FmiSrl.FtpServer.Server/Commands/RetrCommand.cs
+++ b/FmiSrl.FtpServer.Server/Commands/RetrCommand.cs
@@ -36,8 +36,9 @@ public async Task ExecuteAsync(FtpCommandContext context)
     private static async Task ProcessRetrieveAsync(FtpCommandContext context)
     {
         var targetFile = PathHelper.NormalizePath(context.Session.CurrentDirectory, context.Arguments);
+        var entry = await context.FileSystem.GetEntryAsync(context.AuthContext, targetFile);
 
-        if (!await context.FileSystem.FileExistsAsync(context.AuthContext, targetFile))
+        if (entry == null || entry.IsDirectory)
         {
             await context.Session.SendResponseAsync(550, "File not found.");
             return;
@@ -47,7 +48,7 @@ private static async Task ProcessRetrieveAsync(FtpCommandContext context)
 
         try
         {
-            await TransferFileAsync(context, targetFile);
+            await TransferFileAsync(context, targetFile, entry);
         }
         catch (Exception ex)
         {
@@ -61,7 +62,7 @@ private static async Task ProcessRetrieveAsync(FtpCommandContext context)
         }
     }
 
-    private static async Task TransferFileAsync(FtpCommandContext context, string targetFile)
+    private static async Task TransferFileAsync(FtpCommandContext context, string targetFile, FileSystemEntry entry)
     {
         var dataStream = await context.Session.DataConnection!.GetStreamAsync();
 
@@ -70,7 +71,7 @@ private static async Task TransferFileAsync(FtpCommandContext context, string ta
             context.Logger.LogInformation(
                 "Starting transfer of {TargetFile} ({Length} bytes)...",
                 targetFile,
-                fileStream.Length);
+                entry.Size);
             await fileStream.CopyToAsync(dataStream);
             context.Logger.LogInformation("Finished copying {TargetFile} to data stream.", targetFile);
         }
diff --git a/FmiSrl.FtpServer.Server/Commands/SizeCommand.cs b/FmiSrl.FtpServer.Server/Commands/SizeCommand.cs
index 6467412..0fa49f2 100644
--- a/FmiSrl.FtpServer.Server/Commands/SizeCommand.cs
+++ b/FmiSrl.FtpServer.Server/Commands/SizeCommand.cs
@@ -42,21 +42,14 @@ private static async Task ProcessSizeRequestAsync(FtpCommandContext context)
 
     private static async Task TryGetFileSizeAsync(FtpCommandContext context, string targetFile)
     {
-        var directory = Path.GetDirectoryName(targetFile)?.Replace('\\', '/') ?? "/";
-        if (directory == string.Empty)
-        {
-            directory = "/";
-        }
-
-        var entries = await context.FileSystem.GetEntriesAsync(context.AuthContext, directory);
-        var file = entries.FirstOrDefault(e => !e.IsDirectory && e.Name == Path.GetFileName(targetFile));
+        var entry = await context.FileSystem.GetEntryAsync(context.AuthContext, targetFile);
 
-        if (file != null)
+        if (entry != null && !entry.IsDirectory)
         {
-            await context.Session.SendResponseAsync(213, file.Size.ToString(CultureInfo.InvariantCulture));
+            await context.Session.SendResponseAsync(213, entry.Size.ToString(CultureInfo.InvariantCulture));
             return;
         }
 
-        await context.Session.SendResponseAsync(550, "File not found.");
+        await context.Session.SendResponseAsync(550, "File not found or is a directory.");
     }
 }
diff --git a/FmiSrl.FtpServer.Server/Services/PhysicalFileSystemProvider.cs b/FmiSrl.FtpServer.Server/Services/PhysicalFileSystemProvider.cs
index 2afb501..edaa863 100644
--- a/FmiSrl.FtpServer.Server/Services/PhysicalFileSystemProvider.cs
+++ b/FmiSrl.FtpServer.Server/Services/PhysicalFileSystemProvider.cs
@@ -99,6 +99,25 @@ public Task<bool> FileExistsAsync(FtpAuthenticationContext authContext, string p
     public Task<bool> DirectoryExistsAsync(FtpAuthenticationContext authContext, string path) =>
         Task.FromResult(Directory.Exists(GetFullPath(authContext, path)));
 
+    /// <inheritdoc/>
+    public Task<FileSystemEntry?> GetEntryAsync(FtpAuthenticationContext authContext, string path)
+    {
+        var fullPath = GetFullPath(authContext, path);
+        if (File.Exists(fullPath))
+        {
+            var fi = new FileInfo(fullPath);
+            return Task.FromResult<FileSystemEntry?>(new FileSystemEntry(fi.Name, fi.Length, fi.LastWriteTime, false));
+        }
+
+        if (Directory.Exists(fullPath))
+        {
+            var di = new DirectoryInfo(fullPath);
+            return Task.FromResult<FileSystemEntry?>(new FileSystemEntry(di.Name, 0, di.LastWriteTime, true));
+        }
+
+        return Task.FromResult<FileSystemEntry?>(null);
+    }
+
     /// <inheritdoc/>
     public Task RenameAsync(FtpAuthenticationContext authContext, string oldPath, string newPath)
     {
diff --git a/FmiSrl.FtpServer.Tests.Unit/Commands/RetrCommandTests.cs b/FmiSrl.FtpServer.Tests.Unit/Commands/RetrCommandTests.cs
index e7a0ae8..174da0a 100644
--- a/FmiSrl.FtpServer.Tests.Unit/Commands/RetrCommandTests.cs
+++ b/FmiSrl.FtpServer.Tests.Unit/Commands/RetrCommandTests.cs
@@ -50,7 +50,7 @@ public async Task ExecuteAsync_WhenFileNotFound_ShouldReturn550()
     {
         var sut = new RetrCommand();
         _session.DataConnection.Returns(Substitute.For<IFtpDataConnection>());
-        _fileSystem.FileExistsAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Returns(false);
+        _fileSystem.GetEntryAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Returns((FileSystemEntry?)null);
         await sut.ExecuteAsync(_context);
         await _session.Received().SendResponseAsync(550, Arg.Any<string>());
     }
@@ -62,7 +62,8 @@ public async Task ExecuteAsync_WhenSuccess_ShouldReturn226()
         var dataConn = Substitute.For<IFtpDataConnection>();
         dataConn.GetStreamAsync().Returns(new MemoryStream());
         _session.DataConnection.Returns(dataConn);
-        _fileSystem.FileExistsAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Returns(true);
+        _fileSystem.GetEntryAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt")
+            .Returns(new FileSystemEntry("file.txt", 10, DateTime.Now, false));
         _fileSystem.OpenReadAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Returns(new MemoryStream(new byte[10]));
 
         await sut.ExecuteAsync(_context);
@@ -78,7 +79,8 @@ public async Task ExecuteAsync_WhenException_ShouldReturn550()
         var sut = new RetrCommand();
         var dataConn = Substitute.For<IFtpDataConnection>();
         _session.DataConnection.Returns(dataConn);
-        _fileSystem.FileExistsAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Returns(true);
+        _fileSystem.GetEntryAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt")
+            .Returns(new FileSystemEntry("file.txt", 10, DateTime.Now, false));
         dataConn.GetStreamAsync().Throws(new InvalidOperationException());
 
         await sut.ExecuteAsync(_context);
diff --git a/FmiSrl.FtpServer.Tests.Unit/Commands/SizeCommandTests.cs b/FmiSrl.FtpServer.Tests.Unit/Commands/SizeCommandTests.cs
index 9e7e55a..b17f9fd 100644
--- a/FmiSrl.FtpServer.Tests.Unit/Commands/SizeCommandTests.cs
+++ b/FmiSrl.FtpServer.Tests.Unit/Commands/SizeCommandTests.cs
@@ -39,8 +39,8 @@ public async Task ExecuteAsync_WhenArgsEmpty_ShouldReturn501()
     public async Task ExecuteAsync_WhenFileExists_ShouldReturnSize()
     {
         var sut = new SizeCommand();
-        var entries = new[] { new FileSystemEntry("file.txt", 1234, DateTime.Now, false) };
-        _fileSystem.GetEntriesAsync(Arg.Any<FtpAuthenticationContext>(), "/").Returns(entries);
+        var entry = new FileSystemEntry("file.txt", 1234, DateTime.Now, false);
+        _fileSystem.GetEntryAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Returns(entry);
         await sut.ExecuteAsync(_context);
         await _session.Received().SendResponseAsync(213, "1234");
     }
@@ -49,16 +49,16 @@ public async Task ExecuteAsync_WhenFileExists_ShouldReturnSize()
     public async Task ExecuteAsync_WhenFileNotFound_ShouldReturn550()
     {
         var sut = new SizeCommand();
-        _fileSystem.GetEntriesAsync(Arg.Any<FtpAuthenticationContext>(), "/").Returns(Array.Empty<FileSystemEntry>());
+        _fileSystem.GetEntryAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Returns((FileSystemEntry?)null);
         await sut.ExecuteAsync(_context);
-        await _session.Received().SendResponseAsync(550, "File not found.");
+        await _session.Received().SendResponseAsync(550, "File not found or is a directory.");
     }
 
     [Fact]
     public async Task ExecuteAsync_WhenException_ShouldReturn550()
     {
         var sut = new SizeCommand();
-        _fileSystem.GetEntriesAsync(Arg.Any<FtpAuthenticationContext>(), "/").Throws(new InvalidOperationException());
+        _fileSystem.GetEntryAsync(Arg.Any<FtpAuthenticationContext>(), "/file.txt").Throws(new InvalidOperationException());
         await sut.ExecuteAsync(_context);
         await _session.Received().SendResponseAsync(550, "Error getting file size.");
     }
diff --git a/FmiSrl.FtpServer.Tests.Unit/DependencyInjection/DependencyInjectionTests.cs b/FmiSrl.FtpServer.Tests.Unit/DependencyInjection/DependencyInjectionTests.cs
index 491a45e..00937dd 100644
--- a/FmiSrl.FtpServer.Tests.Unit/DependencyInjection/DependencyInjectionTests.cs
+++ b/FmiSrl.FtpServer.Tests.Unit/DependencyInjection/DependencyInjectionTests.cs
@@ -65,6 +65,7 @@ private sealed class DummyFileSystemProvider : IFileSystemProvider
         public Task DeleteDirectoryAsync(FtpAuthenticationContext authContext, string path) => throw new NotImplementedException();
         public Task<bool> FileExistsAsync(FtpAuthenticationContext authContext, string path) => throw new NotImplementedException();
         public Task<bool> DirectoryExistsAsync(FtpAuthenticationContext authContext, string path) => throw new NotImplementedException();
+        public Task<FileSystemEntry?> GetEntryAsync(FtpAuthenticationContext authContext, string path) => throw new NotImplementedException();
         public Task RenameAsync(FtpAuthenticationContext authContext, string oldPath, string newPath) => throw new NotImplementedException();
     }
 
diff --git a/global.json b/global.json
index 6b350c5..95365e3 100644
--- a/global.json
+++ b/global.json
@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "10.0.202",
+    "version": "10.0.203",
     "rollForward": "latestMajor",
     "allowPrerelease": false
   }