diff --git a/samples/JwtAuthentication/JwtAuthApp.Client/JwtAuthApp.Client.csproj b/samples/JwtAuthentication/JwtAuthApp.Client/JwtAuthApp.Client.csproj
index 10b61ef6e..eda654116 100644
--- a/samples/JwtAuthentication/JwtAuthApp.Client/JwtAuthApp.Client.csproj
+++ b/samples/JwtAuthentication/JwtAuthApp.Client/JwtAuthApp.Client.csproj
@@ -3,6 +3,8 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>net7.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/samples/JwtAuthentication/JwtAuthApp.Client/Program.cs b/samples/JwtAuthentication/JwtAuthApp.Client/Program.cs
index 827c672db..ee8977d2a 100644
--- a/samples/JwtAuthentication/JwtAuthApp.Client/Program.cs
+++ b/samples/JwtAuthentication/JwtAuthApp.Client/Program.cs
@@ -124,12 +124,12 @@ public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<R
 
                 AuthenticationTokenStorage.Current.Update(authResult.Token, authResult.Expiration); // NOTE: You can also read the token expiration date from JWT.
 
-                context.CallOptions.Headers.Remove(new Metadata.Entry("Authorization", string.Empty));
+                context.CallOptions.Headers?.Remove(new Metadata.Entry("Authorization", string.Empty));
             }
 
-            if (!context.CallOptions.Headers.Contains(new Metadata.Entry("Authorization", string.Empty)))
+            if (!context.CallOptions.Headers?.Contains(new Metadata.Entry("Authorization", string.Empty)) ?? false)
             {
-                context.CallOptions.Headers.Add("Authorization", "Bearer " + AuthenticationTokenStorage.Current.Token);
+                context.CallOptions.Headers?.Add("Authorization", "Bearer " + AuthenticationTokenStorage.Current.Token);
             }
 
             return await next(context);
@@ -144,7 +144,7 @@ class AuthenticationTokenStorage
 
         private readonly object _syncObject = new object();
 
-        public string Token { get; private set; }
+        public string? Token { get; private set; }
         public DateTimeOffset Expiration { get; private set; }
 
         public bool IsExpired => Token == null || Expiration < DateTimeOffset.Now;