diff --git a/MediaBrowser.Api/HttpHandlers/UserAuthenticationHandler.cs b/MediaBrowser.Api/HttpHandlers/UserAuthenticationHandler.cs
index c0ee2ff0eb..ed588e7762 100644
--- a/MediaBrowser.Api/HttpHandlers/UserAuthenticationHandler.cs
+++ b/MediaBrowser.Api/HttpHandlers/UserAuthenticationHandler.cs
@@ -12,7 +12,7 @@ namespace MediaBrowser.Api.HttpHandlers
     {
         protected override async Task<AuthenticationResult> GetObjectToSerialize()
         {
-            Guid userId = Guid.Parse(await GetFormValue("userId").ConfigureAwait(false));
+            Guid userId = Guid.Parse(await GetFormValue("userid").ConfigureAwait(false));
             User user = Kernel.Instance.Users.First(u => u.Id == userId);
 
             string password = await GetFormValue("password").ConfigureAwait(false);
diff --git a/MediaBrowser.ApiInteraction/ApiClient.cs b/MediaBrowser.ApiInteraction/ApiClient.cs
index f8c0dc761b..ca53c66fcd 100644
--- a/MediaBrowser.ApiInteraction/ApiClient.cs
+++ b/MediaBrowser.ApiInteraction/ApiClient.cs
@@ -654,9 +654,9 @@ namespace MediaBrowser.ApiInteraction
         /// </summary>
         public async Task<AuthenticationResult> AuthenticateUser(Guid userId, string password)
         {
-            string url = ApiUrl + "/UserAuthentication?userId=" + userId;
-            url += "&dataformat=" + SerializationFormat.ToString();
+            string url = ApiUrl + "/UserAuthentication?dataformat=" + SerializationFormat.ToString();
 
+            // Create the post body
             string postContent = string.Format("userid={0}&password={1}", userId, password);
 
             HttpContent content = new StringContent(postContent, Encoding.UTF8, "application/x-www-form-urlencoded");