diff --git a/runtime/CSharp/src/Recognizer.cs b/runtime/CSharp/src/Recognizer.cs
index 1f8e52b1a3..3abbabccc1 100644
--- a/runtime/CSharp/src/Recognizer.cs
+++ b/runtime/CSharp/src/Recognizer.cs
@@ -7,6 +7,7 @@
 using System.Runtime.CompilerServices;
 using Antlr4.Runtime.Atn;
 using Antlr4.Runtime.Misc;
+using Antlr4.Runtime.Sharpen;
 
 namespace Antlr4.Runtime
 {
diff --git a/runtime/CSharp/src/Vocabulary.cs b/runtime/CSharp/src/Vocabulary.cs
index ba5318a00c..ee18daae90 100644
--- a/runtime/CSharp/src/Vocabulary.cs
+++ b/runtime/CSharp/src/Vocabulary.cs
@@ -16,7 +16,7 @@ namespace Antlr4.Runtime
     /// <author>Sam Harwell</author>
     public class Vocabulary : IVocabulary
     {
-        private static readonly string[] EmptyNames = System.Collections.EmptyList<string>();
+        private static readonly string[] EmptyNames = Collections.EmptyList<string>();
 
         /// <summary>
         /// Gets an empty