diff --git a/src/Ocelot/Authentication/Middleware/AuthenticationMiddleware.cs b/src/Ocelot/Authentication/Middleware/AuthenticationMiddleware.cs
index 337fb55b1..41007f688 100644
--- a/src/Ocelot/Authentication/Middleware/AuthenticationMiddleware.cs
+++ b/src/Ocelot/Authentication/Middleware/AuthenticationMiddleware.cs
@@ -29,7 +29,7 @@ public async Task Invoke(HttpContext httpContext)
                     $"{httpContext.Request.Path} is an authenticated route. {MiddlewareName} checking if client is authenticated");
 
                 var token = httpContext.Request.Headers
-                    .First(r => r.Key.Equals("Authorization", StringComparison.OrdinalIgnoreCase));
+                    .FirstOrDefault(r => r.Key.Equals("Authorization", StringComparison.OrdinalIgnoreCase));
 
                 var cacheKey = $"identityToken.{token}";