diff --git a/src/Duende.AccessTokenManagement/AccessTokenHandler.cs b/src/Duende.AccessTokenManagement/AccessTokenHandler.cs
index 7fb1bad..c544006 100644
--- a/src/Duende.AccessTokenManagement/AccessTokenHandler.cs
+++ b/src/Duende.AccessTokenManagement/AccessTokenHandler.cs
@@ -102,6 +102,18 @@ protected virtual async Task SetTokenAsync(HttpRequestMessage request, bool forc
                 }
             }
 
+            // since AccessTokenType above in the token endpoint response (the token_type value) could be case insensitive, but
+            // when we send it as an Authoriization header in the API request it must be case sensitive, we 
+            // are checking for that here and forcing it to the exact casing required.
+            if (scheme.Equals(AuthenticationSchemes.AuthorizationHeaderBearer, System.StringComparison.OrdinalIgnoreCase))
+            {
+                scheme = AuthenticationSchemes.AuthorizationHeaderBearer;
+            }
+            else if (scheme.Equals(AuthenticationSchemes.AuthorizationHeaderDPoP, System.StringComparison.OrdinalIgnoreCase))
+            {
+                scheme = AuthenticationSchemes.AuthorizationHeaderDPoP;
+            }
+
             // checking for null AccessTokenType and falling back to "Bearer" since this might be coming
             // from an old cache/store prior to adding the AccessTokenType property.
             request.SetToken(scheme, token.AccessToken);
diff --git a/src/Duende.AccessTokenManagement/DPoPExtensions.cs b/src/Duende.AccessTokenManagement/DPoPExtensions.cs
index 63828ce..6090b2a 100644
--- a/src/Duende.AccessTokenManagement/DPoPExtensions.cs
+++ b/src/Duende.AccessTokenManagement/DPoPExtensions.cs
@@ -79,6 +79,5 @@ public static bool IsDPoPError(this HttpResponseMessage response)
     public static string GetDPoPUrl(this HttpRequestMessage request)
     {
         return request.RequestUri!.Scheme + "://" + request.RequestUri!.Authority + request.RequestUri!.LocalPath;
-        return request.RequestUri!.Scheme + "://" + request.RequestUri!.Authority + request.RequestUri!.AbsolutePath;
     }
 }
\ No newline at end of file
diff --git a/test/Tests/AccessTokenHandlerTests.cs b/test/Tests/AccessTokenHandlerTests.cs
new file mode 100644
index 0000000..bcabae6
--- /dev/null
+++ b/test/Tests/AccessTokenHandlerTests.cs
@@ -0,0 +1,74 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using RichardSzalay.MockHttp;
+
+namespace Duende.AccessTokenManagement.Tests;
+
+public class AccessTokenHandlerTests 
+{
+    TestDPoPProofService _testDPoPProofService = new TestDPoPProofService();
+    TestHttpMessageHandler _testHttpMessageHandler = new TestHttpMessageHandler();
+
+    AccessTokenHandlerSubject _subject;
+
+    public AccessTokenHandlerTests()
+    {
+        _subject = new AccessTokenHandlerSubject(_testDPoPProofService, new TestDPoPNonceStore(), new TestLoggerProvider().CreateLogger("AccessTokenHandlerSubject"));
+        _subject.InnerHandler = _testHttpMessageHandler;
+    }
+
+    [Fact]
+    public async Task lower_case_token_type_should_be_converted_to_case_sensitive()
+    {
+        var client = new HttpClient(_subject);
+
+        {
+            _subject.AccessToken.AccessTokenType = "bearer";
+
+            var response = await client.GetAsync("https://test/api");
+
+            _testHttpMessageHandler.Request!.Headers.Authorization!.Scheme.ShouldBe("Bearer");
+        }
+        
+        {
+            _subject.AccessToken.AccessTokenType = "dpop";
+
+            var response = await client.GetAsync("https://test/api");
+
+            _testHttpMessageHandler.Request!.Headers.Authorization!.Scheme.ShouldBe("DPoP");
+        }
+    }
+
+    public class TestHttpMessageHandler : HttpMessageHandler
+    {
+        public HttpRequestMessage? Request { get; set; }
+        public HttpResponseMessage Response { get; set; } = new HttpResponseMessage(System.Net.HttpStatusCode.NoContent);
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            Request = request;
+            return Task.FromResult(Response);
+        }
+    }
+
+    public class AccessTokenHandlerSubject : AccessTokenHandler
+    {
+        public ClientCredentialsToken AccessToken { get; set; } = new ClientCredentialsToken
+        {
+            AccessToken = "at",
+            AccessTokenType = "bearer",
+        };
+
+        public AccessTokenHandlerSubject(IDPoPProofService dPoPProofService, IDPoPNonceStore dPoPNonceStore, ILogger logger) : base(dPoPProofService, dPoPNonceStore, logger)
+        {
+        }
+
+        protected override Task<ClientCredentialsToken> GetAccessTokenAsync(bool forceRenewal, CancellationToken cancellationToken)
+        {
+            return Task.FromResult(AccessToken);
+        }
+    }
+}
\ No newline at end of file
diff --git a/test/Tests/ClientTokenManagementApiTests.cs b/test/Tests/ClientTokenManagementApiTests.cs
index 5b3588d..ceaf268 100644
--- a/test/Tests/ClientTokenManagementApiTests.cs
+++ b/test/Tests/ClientTokenManagementApiTests.cs
@@ -1,3 +1,5 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
 
 using Duende.IdentityServer.Configuration;
 using IdentityModel;
diff --git a/test/Tests/ClientTokenManagementTests.cs b/test/Tests/ClientTokenManagementTests.cs
index b44c59f..1d6240d 100644
--- a/test/Tests/ClientTokenManagementTests.cs
+++ b/test/Tests/ClientTokenManagementTests.cs
@@ -1,3 +1,6 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
 using System.Net;
 using System.Text.Json;
 using IdentityModel;
diff --git a/test/Tests/Framework/TestClientAssertionService.cs b/test/Tests/Framework/TestClientAssertionService.cs
index b0d2087..c03a7d3 100644
--- a/test/Tests/Framework/TestClientAssertionService.cs
+++ b/test/Tests/Framework/TestClientAssertionService.cs
@@ -1,3 +1,6 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
 using IdentityModel.Client;
 
 namespace Duende.AccessTokenManagement.Tests;
diff --git a/test/Tests/Framework/TestDPoPNonceStore.cs b/test/Tests/Framework/TestDPoPNonceStore.cs
new file mode 100644
index 0000000..066ecec
--- /dev/null
+++ b/test/Tests/Framework/TestDPoPNonceStore.cs
@@ -0,0 +1,18 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
+
+namespace Duende.AccessTokenManagement.Tests;
+
+public class TestDPoPNonceStore : IDPoPNonceStore
+{
+    public Task<string?> GetNonceAsync(DPoPNonceContext context, CancellationToken cancellationToken = default)
+    {
+        return Task.FromResult<string?>(null);
+    }
+
+    public Task StoreNonceAsync(DPoPNonceContext context, string nonce, CancellationToken cancellationToken = default)
+    {
+        return Task.CompletedTask;
+    }
+}
\ No newline at end of file
diff --git a/test/Tests/UserTokenManagementTests.cs b/test/Tests/UserTokenManagementTests.cs
index 53b443e..e6cf89f 100644
--- a/test/Tests/UserTokenManagementTests.cs
+++ b/test/Tests/UserTokenManagementTests.cs
@@ -1,3 +1,6 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
 using System.Net.Http.Json;
 using System.Text.Json;
 using Duende.AccessTokenManagement.OpenIdConnect;
diff --git a/test/Tests/Usings.cs b/test/Tests/Usings.cs
index bd8299f..42ff96b 100644
--- a/test/Tests/Usings.cs
+++ b/test/Tests/Usings.cs
@@ -1,2 +1,5 @@
+// Copyright (c) Duende Software. All rights reserved.
+// See LICENSE in the project root for license information.
+
 global using Xunit;
 global using Shouldly;
\ No newline at end of file