diff --git a/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Shipped.txt b/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Shipped.txt
index e69de29bb2..7dc5c58110 100644
--- a/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Shipped.txt
+++ b/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Shipped.txt
@@ -0,0 +1 @@
+#nullable enable
diff --git a/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Unshipped.txt b/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Unshipped.txt
index 761ae2d2ff..0d125870ad 100644
--- a/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Unshipped.txt
+++ b/src/OpenTelemetry.Instrumentation.Owin/.publicApi/net462/PublicAPI.Unshipped.txt
@@ -2,9 +2,9 @@ OpenTelemetry.Instrumentation.Owin.OwinEnrichEventType
 OpenTelemetry.Instrumentation.Owin.OwinEnrichEventType.BeginRequest = 0 -> OpenTelemetry.Instrumentation.Owin.OwinEnrichEventType
 OpenTelemetry.Instrumentation.Owin.OwinEnrichEventType.EndRequest = 1 -> OpenTelemetry.Instrumentation.Owin.OwinEnrichEventType
 OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions
-OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.Enrich.get -> System.Action<System.Diagnostics.Activity, OpenTelemetry.Instrumentation.Owin.OwinEnrichEventType, Microsoft.Owin.IOwinContext, System.Exception>
+OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.Enrich.get -> System.Action<System.Diagnostics.Activity!, OpenTelemetry.Instrumentation.Owin.OwinEnrichEventType, Microsoft.Owin.IOwinContext!, System.Exception?>?
 OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.Enrich.set -> void
-OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.Filter.get -> System.Func<Microsoft.Owin.IOwinContext, bool>
+OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.Filter.get -> System.Func<Microsoft.Owin.IOwinContext!, bool>?
 OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.Filter.set -> void
 OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.OwinInstrumentationOptions() -> void
 OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.RecordException.get -> bool
@@ -12,7 +12,7 @@ OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions.RecordException.se
 OpenTelemetry.Metrics.OwinInstrumentationMeterProviderBuilderExtensions
 OpenTelemetry.Trace.TracerProviderBuilderExtensions
 Owin.AppBuilderExtensions
-static OpenTelemetry.Metrics.OwinInstrumentationMeterProviderBuilderExtensions.AddOwinInstrumentation(this OpenTelemetry.Metrics.MeterProviderBuilder builder) -> OpenTelemetry.Metrics.MeterProviderBuilder
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.AddOwinInstrumentation(this OpenTelemetry.Trace.TracerProviderBuilder builder) -> OpenTelemetry.Trace.TracerProviderBuilder
-static OpenTelemetry.Trace.TracerProviderBuilderExtensions.AddOwinInstrumentation(this OpenTelemetry.Trace.TracerProviderBuilder builder, System.Action<OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions> configure) -> OpenTelemetry.Trace.TracerProviderBuilder
-static Owin.AppBuilderExtensions.UseOpenTelemetry(this Owin.IAppBuilder appBuilder) -> Owin.IAppBuilder
\ No newline at end of file
+static OpenTelemetry.Metrics.OwinInstrumentationMeterProviderBuilderExtensions.AddOwinInstrumentation(this OpenTelemetry.Metrics.MeterProviderBuilder! builder) -> OpenTelemetry.Metrics.MeterProviderBuilder!
+static OpenTelemetry.Trace.TracerProviderBuilderExtensions.AddOwinInstrumentation(this OpenTelemetry.Trace.TracerProviderBuilder! builder) -> OpenTelemetry.Trace.TracerProviderBuilder!
+static OpenTelemetry.Trace.TracerProviderBuilderExtensions.AddOwinInstrumentation(this OpenTelemetry.Trace.TracerProviderBuilder! builder, System.Action<OpenTelemetry.Instrumentation.Owin.OwinInstrumentationOptions!>? configure) -> OpenTelemetry.Trace.TracerProviderBuilder!
+static Owin.AppBuilderExtensions.UseOpenTelemetry(this Owin.IAppBuilder! appBuilder) -> Owin.IAppBuilder!
\ No newline at end of file
diff --git a/src/OpenTelemetry.Instrumentation.Owin/Implementation/DiagnosticsMiddleware.cs b/src/OpenTelemetry.Instrumentation.Owin/Implementation/DiagnosticsMiddleware.cs
index 9c15a7c40c..6b435ef87b 100644
--- a/src/OpenTelemetry.Instrumentation.Owin/Implementation/DiagnosticsMiddleware.cs
+++ b/src/OpenTelemetry.Instrumentation.Owin/Implementation/DiagnosticsMiddleware.cs
@@ -77,7 +77,7 @@ private static void BeginRequest(IOwinContext owinContext)
         var textMapPropagator = Propagators.DefaultTextMapPropagator;
         var ctx = textMapPropagator.Extract(default, owinContext.Request, OwinRequestHeaderValuesGetter);
 
-        Activity activity = OwinInstrumentationActivitySource.ActivitySource.StartActivity(
+        Activity? activity = OwinInstrumentationActivitySource.ActivitySource.StartActivity(
             OwinInstrumentationActivitySource.IncomingRequestActivityName,
             ActivityKind.Server,
             ctx.ActivityContext);
@@ -123,7 +123,7 @@ private static void BeginRequest(IOwinContext owinContext)
 
                 try
                 {
-                    OwinInstrumentationActivitySource.Options.Enrich?.Invoke(
+                    OwinInstrumentationActivitySource.Options?.Enrich?.Invoke(
                         activity,
                         OwinEnrichEventType.BeginRequest,
                         owinContext,
@@ -147,7 +147,7 @@ private static void BeginRequest(IOwinContext owinContext)
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static void RequestEnd(IOwinContext owinContext, Exception exception, long startTimestamp)
+    private static void RequestEnd(IOwinContext owinContext, Exception? exception, long startTimestamp)
     {
         if (owinContext.Environment.TryGetValue(ContextKey, out object context)
             && context is Activity activity)
@@ -165,7 +165,7 @@ private static void RequestEnd(IOwinContext owinContext, Exception exception, lo
                 {
                     activity.SetStatus(Status.Error);
 
-                    if (OwinInstrumentationActivitySource.Options.RecordException)
+                    if (OwinInstrumentationActivitySource.Options != null && OwinInstrumentationActivitySource.Options.RecordException)
                     {
                         activity.RecordException(exception);
                     }
@@ -179,7 +179,7 @@ private static void RequestEnd(IOwinContext owinContext, Exception exception, lo
 
                 try
                 {
-                    OwinInstrumentationActivitySource.Options.Enrich?.Invoke(
+                    OwinInstrumentationActivitySource.Options?.Enrich?.Invoke(
                         activity,
                         OwinEnrichEventType.EndRequest,
                         owinContext,
diff --git a/src/OpenTelemetry.Instrumentation.Owin/Implementation/OwinInstrumentationActivitySource.cs b/src/OpenTelemetry.Instrumentation.Owin/Implementation/OwinInstrumentationActivitySource.cs
index 7537360628..319d337db7 100644
--- a/src/OpenTelemetry.Instrumentation.Owin/Implementation/OwinInstrumentationActivitySource.cs
+++ b/src/OpenTelemetry.Instrumentation.Owin/Implementation/OwinInstrumentationActivitySource.cs
@@ -15,7 +15,7 @@ internal static class OwinInstrumentationActivitySource
 
     private static readonly Version Version = AssemblyName.Version;
 
-    public static ActivitySource ActivitySource { get; } = new ActivitySource(ActivitySourceName, Version.ToString());
+    public static ActivitySource ActivitySource { get; } = new(ActivitySourceName, Version.ToString());
 
-    public static OwinInstrumentationOptions Options { get; set; }
+    public static OwinInstrumentationOptions? Options { get; set; }
 }
diff --git a/src/OpenTelemetry.Instrumentation.Owin/OpenTelemetry.Instrumentation.Owin.csproj b/src/OpenTelemetry.Instrumentation.Owin/OpenTelemetry.Instrumentation.Owin.csproj
index 19e66285f7..7e5c9223a6 100644
--- a/src/OpenTelemetry.Instrumentation.Owin/OpenTelemetry.Instrumentation.Owin.csproj
+++ b/src/OpenTelemetry.Instrumentation.Owin/OpenTelemetry.Instrumentation.Owin.csproj
@@ -4,7 +4,6 @@
     <Description>OpenTelemetry instrumentation for OWIN</Description>
     <PackageTags>$(PackageTags);distributed-tracing;OWIN</PackageTags>
     <MinVerTagPrefix>Instrumentation.Owin-</MinVerTagPrefix>
-    <Nullable>disable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/OpenTelemetry.Instrumentation.Owin/OwinInstrumentationOptions.cs b/src/OpenTelemetry.Instrumentation.Owin/OwinInstrumentationOptions.cs
index 3c1ba76356..57f98e812d 100644
--- a/src/OpenTelemetry.Instrumentation.Owin/OwinInstrumentationOptions.cs
+++ b/src/OpenTelemetry.Instrumentation.Owin/OwinInstrumentationOptions.cs
@@ -18,12 +18,12 @@ public class OwinInstrumentationOptions
     /// If Filter returns true, the request is collected.
     /// If Filter returns false or throw exception, the request is filtered out.
     /// </summary>
-    public Func<IOwinContext, bool> Filter { get; set; }
+    public Func<IOwinContext, bool>? Filter { get; set; }
 
     /// <summary>
     /// Gets or sets an action to enrich the <see cref="Activity"/> created by the instrumentation.
     /// </summary>
-    public Action<Activity, OwinEnrichEventType, IOwinContext, Exception> Enrich { get; set; }
+    public Action<Activity, OwinEnrichEventType, IOwinContext, Exception?>? Enrich { get; set; }
 
     /// <summary>
     /// Gets or sets a value indicating whether the exception will be recorded as <see cref="ActivityEvent"/> or not.
diff --git a/src/OpenTelemetry.Instrumentation.Owin/TracerProviderBuilderExtensions.cs b/src/OpenTelemetry.Instrumentation.Owin/TracerProviderBuilderExtensions.cs
index 6fe62ea930..ca55244d23 100644
--- a/src/OpenTelemetry.Instrumentation.Owin/TracerProviderBuilderExtensions.cs
+++ b/src/OpenTelemetry.Instrumentation.Owin/TracerProviderBuilderExtensions.cs
@@ -28,7 +28,7 @@ public static TracerProviderBuilder AddOwinInstrumentation(this TracerProviderBu
     /// <returns>The instance of <see cref="TracerProviderBuilder"/> to chain the calls.</returns>
     public static TracerProviderBuilder AddOwinInstrumentation(
         this TracerProviderBuilder builder,
-        Action<OwinInstrumentationOptions> configure)
+        Action<OwinInstrumentationOptions>? configure)
     {
         Guard.ThrowIfNull(builder);
 
diff --git a/test/OpenTelemetry.Instrumentation.Owin.Tests/Controllers/TestController.cs b/test/OpenTelemetry.Instrumentation.Owin.Tests/Controllers/TestController.cs
index bf7f20b9ae..d6d9145462 100644
--- a/test/OpenTelemetry.Instrumentation.Owin.Tests/Controllers/TestController.cs
+++ b/test/OpenTelemetry.Instrumentation.Owin.Tests/Controllers/TestController.cs
@@ -8,7 +8,7 @@ namespace OpenTelemetry.Instrumentation.Owin.Tests.Controllers;
 public class TestController : ApiController
 {
     // GET api/test/{id}
-    public string Get(string id = null)
+    public string Get(string? id = null)
     {
         return $"id:{id}";
     }
diff --git a/test/OpenTelemetry.Instrumentation.Owin.Tests/DiagnosticsMiddlewareTests.cs b/test/OpenTelemetry.Instrumentation.Owin.Tests/DiagnosticsMiddlewareTests.cs
index fa89a01b00..d2111ab468 100644
--- a/test/OpenTelemetry.Instrumentation.Owin.Tests/DiagnosticsMiddlewareTests.cs
+++ b/test/OpenTelemetry.Instrumentation.Owin.Tests/DiagnosticsMiddlewareTests.cs
@@ -22,19 +22,18 @@ namespace OpenTelemetry.Instrumentation.Owin.Tests;
 public class DiagnosticsMiddlewareTests : IDisposable
 {
     private readonly Uri serviceBaseUri;
-    private readonly IDisposable listener;
+    private readonly IDisposable? listener;
     private readonly EventWaitHandle requestCompleteHandle = new(false, EventResetMode.AutoReset);
 
     public DiagnosticsMiddlewareTests()
     {
         Random random = new Random();
         var retryCount = 5;
-        while (retryCount > 0)
+        do
         {
+            this.serviceBaseUri = new Uri($"http://localhost:{random.Next(2000, 5000)}/");
             try
             {
-                this.serviceBaseUri = new Uri($"http://localhost:{random.Next(2000, 5000)}/");
-
                 this.listener = WebApp.Start(
                     this.serviceBaseUri.ToString(),
                     appBuilder =>
@@ -81,6 +80,7 @@ public DiagnosticsMiddlewareTests()
                 retryCount--;
             }
         }
+        while (retryCount > 0);
 
         if (this.listener == null)
         {
diff --git a/test/OpenTelemetry.Instrumentation.Owin.Tests/OpenTelemetry.Instrumentation.Owin.Tests.csproj b/test/OpenTelemetry.Instrumentation.Owin.Tests/OpenTelemetry.Instrumentation.Owin.Tests.csproj
index 1ef3fee142..e61f3950e7 100644
--- a/test/OpenTelemetry.Instrumentation.Owin.Tests/OpenTelemetry.Instrumentation.Owin.Tests.csproj
+++ b/test/OpenTelemetry.Instrumentation.Owin.Tests/OpenTelemetry.Instrumentation.Owin.Tests.csproj
@@ -3,7 +3,6 @@
   <PropertyGroup>
     <Description>Unit test project for OpenTelemetry OWIN instrumentation</Description>
     <TargetFrameworks>$(NetFrameworkMinimumSupportedVersion)</TargetFrameworks>
-    <Nullable>disable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>