diff --git a/src/csharp/Grpc.Microbenchmarks/CompletionRegistryBenchmark.cs b/src/csharp/Grpc.Microbenchmarks/CompletionRegistryBenchmark.cs
index c84473830c6..bb57a6968fa 100644
--- a/src/csharp/Grpc.Microbenchmarks/CompletionRegistryBenchmark.cs
+++ b/src/csharp/Grpc.Microbenchmarks/CompletionRegistryBenchmark.cs
@@ -51,7 +51,7 @@ namespace Grpc.Microbenchmarks
 
         private void ThreadBody(int iterations, CompletionRegistry optionalSharedRegistry)
         {
-            var completionRegistry = optionalSharedRegistry ?? new CompletionRegistry(environment, () => BatchContextSafeHandle.Create(), () => RequestCallContextSafeHandle.Create());
+            var completionRegistry = optionalSharedRegistry ?? new CompletionRegistry(environment, () => throw new NotImplementedException(), () => throw new NotImplementedException());
             var ctx = BatchContextSafeHandle.Create();
   
             var stopwatch = Stopwatch.StartNew();
diff --git a/src/csharp/Grpc.Microbenchmarks/SendMessageBenchmark.cs b/src/csharp/Grpc.Microbenchmarks/SendMessageBenchmark.cs
index f16113539a1..390c062298d 100644
--- a/src/csharp/Grpc.Microbenchmarks/SendMessageBenchmark.cs
+++ b/src/csharp/Grpc.Microbenchmarks/SendMessageBenchmark.cs
@@ -52,7 +52,7 @@ namespace Grpc.Microbenchmarks
 
         private void ThreadBody(int iterations, int payloadSize)
         {
-            var completionRegistry = new CompletionRegistry(environment, () => environment.BatchContextPool.Lease(), () => RequestCallContextSafeHandle.Create());
+            var completionRegistry = new CompletionRegistry(environment, () => environment.BatchContextPool.Lease(), () => throw new NotImplementedException());
             var cq = CompletionQueueSafeHandle.CreateAsync(completionRegistry);
             var call = CreateFakeCall(cq);