diff --git a/src/Core/Extensions/Http.cs b/src/Core/Extensions/Http.cs
index 439f1ff..4a17b71 100644
--- a/src/Core/Extensions/Http.cs
+++ b/src/Core/Extensions/Http.cs
@@ -20,9 +20,10 @@ internal static async Task ExecuteHttpProxyOperationAsync(this HttpContext conte
 
             try
             {
-                var httpClient = context.RequestServices
-                    .GetService<IHttpClientFactory>()
-                    .CreateClient(options?.HttpClientName ?? Helpers.HttpProxyClientName);
+                var clientFactory = context.RequestServices.GetService<IHttpClientFactory>()
+                ?? throw new InvalidOperationException("IHttpClientFactory not registered. You need to add builder.Services.AddHttpClient(); during startup");
+
+                var httpClient = clientFactory.CreateClient(options?.HttpClientName ?? Helpers.HttpProxyClientName);
 
                 // If `true`, this proxy call has been intercepted.
                 if(options?.Intercept != null && await options.Intercept(context).ConfigureAwait(false))