diff --git a/csharp/autobuilder/Semmle.Autobuild.Shared/Autobuilder.cs b/csharp/autobuilder/Semmle.Autobuild.Shared/Autobuilder.cs
index 1e8f58c45b7..d17214c5b50 100644
--- a/csharp/autobuilder/Semmle.Autobuild.Shared/Autobuilder.cs
+++ b/csharp/autobuilder/Semmle.Autobuild.Shared/Autobuilder.cs
@@ -146,7 +146,7 @@ namespace Semmle.Autobuild.Shared
         /// solution file and tools.
         /// </summary>
         /// <param name="options">The command line options.</param>
-        public Autobuilder(IBuildActions actions, AutobuildOptions options)
+        protected Autobuilder(IBuildActions actions, AutobuildOptions options)
         {
             Actions = actions;
             Options = options;
diff --git a/csharp/extractor/Semmle.Extraction.CIL.Driver/Program.cs b/csharp/extractor/Semmle.Extraction.CIL.Driver/Program.cs
index cff82d38d81..664322758c4 100644
--- a/csharp/extractor/Semmle.Extraction.CIL.Driver/Program.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL.Driver/Program.cs
@@ -39,7 +39,7 @@ namespace Semmle.Extraction.CIL.Driver
 
             var options = new ExtractorOptions(args);
             var layout = new Layout();
-            var logger = new ConsoleLogger(options.Verbosity);
+            using var logger = new ConsoleLogger(options.Verbosity);
 
             var actions = options.
                 AssembliesToExtract.Select(asm => asm.filename).
diff --git a/csharp/extractor/Semmle.Extraction.CIL/Context.cs b/csharp/extractor/Semmle.Extraction.CIL/Context.cs
index 58b7ac9164d..825a05b5ad1 100644
--- a/csharp/extractor/Semmle.Extraction.CIL/Context.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Context.cs
@@ -125,7 +125,7 @@ namespace Semmle.Extraction.CIL
     {
         public Context cx;
 
-        public GenericContext(Context cx)
+        protected GenericContext(Context cx)
         {
             this.cx = cx;
         }
diff --git a/csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs b/csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs
index 6aa83385540..ccf1e2046f6 100644
--- a/csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs
+++ b/csharp/extractor/Semmle.Extraction.CIL/Entities/Type.cs
@@ -963,7 +963,7 @@ namespace Semmle.Extraction.CIL.Entities
     {
         protected readonly GenericContext gc;
 
-        public TypeParameter(GenericContext gc) : base(gc.cx)
+        protected TypeParameter(GenericContext gc) : base(gc.cx)
         {
             this.gc = gc;
         }
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs
index ebe9242239b..7f1310a61a1 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs
@@ -9,7 +9,7 @@ namespace Semmle.Extraction.CSharp.Entities
 {
     public abstract class Method : CachedSymbol<IMethodSymbol>, IExpressionParentEntity, IStatementParentEntity
     {
-        public Method(Context cx, IMethodSymbol init)
+        protected Method(Context cx, IMethodSymbol init)
             : base(cx, init) { }
 
         protected void PopulateParameters()
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Symbol.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Symbol.cs
index d56e1ff3451..095d914eb32 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Symbol.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Symbol.cs
@@ -11,7 +11,7 @@ namespace Semmle.Extraction.CSharp.Entities
 {
     public abstract class CachedSymbol<T> : CachedEntity<T> where T : ISymbol
     {
-        public CachedSymbol(Context cx, T init)
+        protected CachedSymbol(Context cx, T init)
             : base(cx, init) { }
 
         public virtual Type ContainingType => symbol.ContainingType != null ? Type.Create(Context, symbol.ContainingType) : null;
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Type.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Type.cs
index b1186072c64..c2119b6eaf7 100644
--- a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Type.cs
+++ b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Type.cs
@@ -33,7 +33,7 @@ namespace Semmle.Extraction.CSharp.Entities
 
     public abstract class Type : CachedSymbol<ITypeSymbol>
     {
-        public Type(Context cx, ITypeSymbol init)
+        protected Type(Context cx, ITypeSymbol init)
             : base(cx, init) { }
 
         public virtual AnnotatedType ElementType => default(AnnotatedType);
@@ -336,7 +336,7 @@ namespace Semmle.Extraction.CSharp.Entities
 
     abstract class Type<T> : Type where T : ITypeSymbol
     {
-        public Type(Context cx, T init)
+        protected Type(Context cx, T init)
             : base(cx, init) { }
 
         public new T symbol => (T)base.symbol;
diff --git a/csharp/extractor/Semmle.Extraction/Entities/Location.cs b/csharp/extractor/Semmle.Extraction/Entities/Location.cs
index d499e68c64f..f699a135516 100644
--- a/csharp/extractor/Semmle.Extraction/Entities/Location.cs
+++ b/csharp/extractor/Semmle.Extraction/Entities/Location.cs
@@ -3,7 +3,7 @@ namespace Semmle.Extraction.Entities
 {
     public abstract class Location : CachedEntity<Microsoft.CodeAnalysis.Location?>
     {
-        public Location(Context cx, Microsoft.CodeAnalysis.Location? init)
+        protected Location(Context cx, Microsoft.CodeAnalysis.Location? init)
             : base(cx, init) { }
 
         public static Location Create(Context cx, Microsoft.CodeAnalysis.Location? loc) =>
diff --git a/csharp/extractor/Semmle.Extraction/FreshEntity.cs b/csharp/extractor/Semmle.Extraction/FreshEntity.cs
index b99ae6251c6..c8e793b68f3 100644
--- a/csharp/extractor/Semmle.Extraction/FreshEntity.cs
+++ b/csharp/extractor/Semmle.Extraction/FreshEntity.cs
@@ -9,7 +9,7 @@ namespace Semmle.Extraction
     {
         protected readonly Context cx;
 
-        public FreshEntity(Context cx)
+        protected FreshEntity(Context cx)
         {
             this.cx = cx;
             cx.AddFreshLabel(this);
diff --git a/csharp/extractor/Semmle.Extraction/Symbol.cs b/csharp/extractor/Semmle.Extraction/Symbol.cs
index 5b33ba11b46..d118551935e 100644
--- a/csharp/extractor/Semmle.Extraction/Symbol.cs
+++ b/csharp/extractor/Semmle.Extraction/Symbol.cs
@@ -9,7 +9,7 @@ namespace Semmle.Extraction
     /// <typeparam name="Initializer">The type of the symbol.</typeparam>
     public abstract class CachedEntity<Initializer> : ICachedEntity
     {
-        public CachedEntity(Context context, Initializer init)
+        protected CachedEntity(Context context, Initializer init)
         {
             Context = context;
             symbol = init;