diff --git a/Source/DafnyCore/DafnyConsolePrinter.cs b/Source/DafnyCore/DafnyConsolePrinter.cs
index 36bb9f2151..8a22e60103 100644
--- a/Source/DafnyCore/DafnyConsolePrinter.cs
+++ b/Source/DafnyCore/DafnyConsolePrinter.cs
@@ -69,7 +69,7 @@ private string GetFileLine(Uri uri, int lineIndex) {
         // Note: This is not guaranteed to be the same file that Dafny parsed. To ensure that, Dafny should keep
         // an in-memory version of each file it parses.
         var file = DafnyFile.CreateAndValidate(new ErrorReporterSink(options), OnDiskFileSystem.Instance, options, uri, Token.NoToken);
-        var reader = file.GetContent();
+        using var reader = file.GetContent();
         lines = Util.Lines(reader).ToList();
       } catch (Exception) {
         lines = new List<string>();
diff --git a/Source/DafnyDriver.Test/FormatterCommandTest.cs b/Source/DafnyDriver.Test/FormatterCommandTest.cs
new file mode 100644
index 0000000000..cd3ae0260a
--- /dev/null
+++ b/Source/DafnyDriver.Test/FormatterCommandTest.cs
@@ -0,0 +1,65 @@
+using System.Diagnostics;
+using System.IO.Pipelines;
+using System.Reactive.Concurrency;
+using System.Reflection;
+using System.Text;
+using Microsoft.Dafny;
+using Microsoft.Extensions.Logging.Abstractions;
+using OmniSharp.Extensions.JsonRpc;
+using OmniSharp.Extensions.JsonRpc.Client;
+using OmniSharp.Extensions.JsonRpc.Serialization;
+using OmniSharp.Extensions.LanguageServer.Protocol.Client.Capabilities;
+using OmniSharp.Extensions.LanguageServer.Protocol.Models;
+
+namespace DafnyDriver.Test;
+
+public class FormatterCommandTest {
+  [Fact]
+  public async Task GitIssueVSCode452FormattingWorksOnBigFiles() {
+    // We write to a temporary file
+    var oneSource = (int i) => $@"function Test{i}(x: int): int
+// This returns {i} if x is greater than 20
+{{
+  if x < 10 then
+                  0
+                  else if x < 20 then
+                                       1
+                                          else {i}
+}}
+
+";
+
+    var oneSourceFormatted = (int i) => $@"function Test{i}(x: int): int
+  // This returns {i} if x is greater than 20
+{{
+  if x < 10 then
+    0
+  else if x < 20 then
+    1
+  else {i}
+}}
+
+";
+    var source = "";
+    var sourceFormatted = "";
+    for (var i = 0; i < 1000; i++) {
+      source += oneSource(i);
+      sourceFormatted += oneSourceFormatted(i);
+    }
+
+    var file = Path.GetTempFileName() + ".dfy";
+
+    await File.WriteAllTextAsync(file, source);
+    StringWriter strWriter = new StringWriter();
+    var options = DafnyOptions.Create(strWriter, null,
+      file
+      );
+
+    var exitValue = await FormatCommand.DoFormatting(options);
+    Assert.Equal(0, (int)exitValue);
+
+    var result = await File.ReadAllTextAsync(file);
+    Assert.Equal(sourceFormatted, result);
+    File.Delete(file);
+  }
+}
diff --git a/Source/DafnyDriver/Commands/FormatCommand.cs b/Source/DafnyDriver/Commands/FormatCommand.cs
index 7782a1aa78..62ba02ef9e 100644
--- a/Source/DafnyDriver/Commands/FormatCommand.cs
+++ b/Source/DafnyDriver/Commands/FormatCommand.cs
@@ -9,7 +9,7 @@
 
 namespace Microsoft.Dafny;
 
-static class FormatCommand {
+public static class FormatCommand {
 
   public static IEnumerable<Option> Options => DafnyCommands.FormatOptions;
 
@@ -72,8 +72,9 @@ public static async Task<ExitValue> DoFormatting(DafnyOptions options) {
           OnDiskFileSystem.Instance, options, new Uri(tempFileName), Token.NoToken);
       }
 
-      using var content = dafnyFile.GetContent();
+      var content = dafnyFile.GetContent();
       var originalText = await content.ReadToEndAsync();
+      content.Close(); // Manual closing because we want to overwrite
       dafnyFile.GetContent = () => new StringReader(originalText);
       // Might not be totally optimized but let's do that for now
       var err = DafnyMain.Parse(new List<DafnyFile> { dafnyFile }, programName, options, out var dafnyProgram);
diff --git a/Source/DafnyLanguageServer/Workspace/LanguageServerFilesystem.cs b/Source/DafnyLanguageServer/Workspace/LanguageServerFilesystem.cs
index 03fdcab515..a545ba4197 100644
--- a/Source/DafnyLanguageServer/Workspace/LanguageServerFilesystem.cs
+++ b/Source/DafnyLanguageServer/Workspace/LanguageServerFilesystem.cs
@@ -38,7 +38,8 @@ public bool OpenDocument(TextDocumentItem document) {
     string existingText = "";
     try {
       if (OnDiskFileSystem.Instance.Exists(uri)) {
-        existingText = OnDiskFileSystem.Instance.ReadFile(uri).ReadToEnd();
+        using var fileStream = OnDiskFileSystem.Instance.ReadFile(uri);
+        existingText = fileStream.ReadToEnd();
       }
     } catch (IOException) {
       // If we don't manage to detect whether this document already existed ond disc,
diff --git a/Source/DafnyPipeline.Test/FormatterIssues.cs b/Source/DafnyPipeline.Test/FormatterIssues.cs
index 7cfd8e3a5f..18bad05f7c 100644
--- a/Source/DafnyPipeline.Test/FormatterIssues.cs
+++ b/Source/DafnyPipeline.Test/FormatterIssues.cs
@@ -1,4 +1,6 @@
-using JetBrains.Annotations;
+using System;
+using System.IO;
+using JetBrains.Annotations;
 using Xunit;
 using Xunit.Abstractions;