diff --git a/Activout.RestClient.Test.Json/RestClientTests.cs b/Activout.RestClient.Test.Json/RestClientTests.cs
index c642a41..0bf9324 100644
--- a/Activout.RestClient.Test.Json/RestClientTests.cs
+++ b/Activout.RestClient.Test.Json/RestClientTests.cs
@@ -112,6 +112,7 @@ public async Task TestErrorAsync(JsonImplementation jsonImplementation)
 
         Assert.Equal(HttpStatusCode.NotFound, exception.StatusCode);
         var error = exception.GetErrorResponse<ErrorResponse>();
+        Assert.NotNull(error);
         Assert.Equal(34, error.Errors[0].Code);
         Assert.Equal("Sorry, that page does not exist", error.Errors[0].Message);
     }
@@ -165,6 +166,7 @@ public void TestErrorSync(JsonImplementation jsonImplementation)
         Assert.Equal("Sorry, that page does not exist", message);
 
         var error = exception.GetErrorResponse<ErrorResponse>();
+        Assert.NotNull(error);
         Assert.Equal(34, error.Errors[0].Code);
         Assert.Equal("Sorry, that page does not exist", error.Errors[0].Message);
     }
diff --git a/Activout.RestClient.Xml.Test/ErrorResponseXmlTest.cs b/Activout.RestClient.Xml.Test/ErrorResponseXmlTest.cs
index 8b84a26..74d0ff9 100644
--- a/Activout.RestClient.Xml.Test/ErrorResponseXmlTest.cs
+++ b/Activout.RestClient.Xml.Test/ErrorResponseXmlTest.cs
@@ -51,6 +51,7 @@ public async Task TestErrorResponse_Xml_BadRequest(string mediaType)
         Assert.NotNull(exception.ErrorResponse);
         Assert.IsType<XmlErrorResponse>(exception.ErrorResponse);
         var errorResponse = exception.GetErrorResponse<XmlErrorResponse>();
+        Assert.NotNull(errorResponse);
         Assert.Equal(400, errorResponse.Code);
         Assert.Equal("Invalid request parameter", errorResponse.Message);
     }
diff --git a/Activout.RestClient/RestClientException.cs b/Activout.RestClient/RestClientException.cs
index 66084aa..a2711d1 100644
--- a/Activout.RestClient/RestClientException.cs
+++ b/Activout.RestClient/RestClientException.cs
@@ -1,39 +1,40 @@
-#nullable disable
 using System;
 using System.Net;
 
-namespace Activout.RestClient
+namespace Activout.RestClient;
+
+public class RestClientException : Exception
 {
-    public class RestClientException : Exception
+    public RestClientException(Uri? requestUri, HttpStatusCode statusCode, object? errorResponse)
+        : base(errorResponse?.ToString())
     {
-        public RestClientException(Uri requestUri, HttpStatusCode statusCode, object errorResponse) : base(errorResponse?.ToString())
-        {
-            RequestUri = requestUri;
-            StatusCode = statusCode;
-            ErrorResponse = errorResponse;
-        }
+        RequestUri = requestUri;
+        StatusCode = statusCode;
+        ErrorResponse = errorResponse;
+    }
 
-        public RestClientException(Uri requestUri, HttpStatusCode statusCode, string errorResponse, Exception innerException) : base(
-            errorResponse, innerException)
-        {
-            RequestUri = requestUri;
-            StatusCode = statusCode;
-            ErrorResponse = errorResponse;
-        }
+    public RestClientException(Uri? requestUri, HttpStatusCode statusCode, string? errorResponse,
+        Exception? innerException)
+        : base(errorResponse, innerException)
+    {
+        RequestUri = requestUri;
+        StatusCode = statusCode;
+        ErrorResponse = errorResponse;
+    }
 
-        public Uri RequestUri { get; }
-        public HttpStatusCode StatusCode { get; }
+    public Uri? RequestUri { get; }
+    public HttpStatusCode StatusCode { get; }
 
-        public object ErrorResponse { get; }
+    public object? ErrorResponse { get; }
 
-        public T GetErrorResponse<T>()
-        {
-            return (T)ErrorResponse;
-        }
+    public T? GetErrorResponse<T>()
+    {
+        return (T?)ErrorResponse;
+    }
 
-        public override string ToString()
-        {
-            return $"{base.ToString()}, {nameof(RequestUri)}: {RequestUri}, {nameof(StatusCode)}: {StatusCode}, {nameof(ErrorResponse)}: {ErrorResponse}";
-        }
+    public override string ToString()
+    {
+        return
+            $"{base.ToString()}, {nameof(RequestUri)}: {RequestUri}, {nameof(StatusCode)}: {StatusCode}, {nameof(ErrorResponse)}: {ErrorResponse}";
     }
 }
\ No newline at end of file