diff --git a/src/Microsoft.Identity.Web/TokenAcquisition.cs b/src/Microsoft.Identity.Web/TokenAcquisition.cs
index b08b9d52d..af05852a0 100644
--- a/src/Microsoft.Identity.Web/TokenAcquisition.cs
+++ b/src/Microsoft.Identity.Web/TokenAcquisition.cs
@@ -540,12 +540,8 @@ public void ReplyForbiddenWithWwwAuthenticateHeader(IEnumerable<string> scopes,
             var httpResponse = CurrentHttpContext.Response;
             var headers = httpResponse.Headers;
             httpResponse.StatusCode = (int)HttpStatusCode.Forbidden;
-            if (headers.ContainsKey(HeaderNames.WWWAuthenticate))
-            {
-                headers.Remove(HeaderNames.WWWAuthenticate);
-            }
 
-            headers.Add(HeaderNames.WWWAuthenticate, v);
+            headers[HeaderNames.WWWAuthenticate] = v;
         }
 
         private static bool AcceptedTokenVersionMismatch(MsalUiRequiredException msalSeviceException)