diff --git a/wp-includes/ms-default-filters.php b/wp-includes/ms-default-filters.php
index d574c88820..c05ed88092 100644
--- a/wp-includes/ms-default-filters.php
+++ b/wp-includes/ms-default-filters.php
@@ -2,7 +2,6 @@
 // Users
 add_filter ( 'wpmu_validate_user_signup', 'signup_nonce_check' );
 add_action ( 'init', 'maybe_add_existing_user_to_blog' );
-add_filter ( 'wp_authenticate_user', 'wordpressmu_authenticate_siteadmin', 10, 2 );
 add_action ( 'wpmu_new_user', 'newuser_notify_siteadmin' );
 add_action ( 'wpmu_activate_user', 'add_new_user_to_blog', 10, 3 );
 add_action ( 'sanitize_user', 'strtolower_usernames', 10, 3 );
diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index 8693588eac..5c17cd0dc0 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -1747,15 +1747,6 @@ function upload_is_file_too_big( $upload ) {
 	return $upload;
 }
 
-function wordpressmu_authenticate_siteadmin( $user, $password = '' ) {
-	if ( is_super_admin( $user->user_login ) == false && ( $primary_blog = get_usermeta( $user->user_id, "primary_blog" ) ) ) {
-		$details = get_blog_details( $primary_blog );
-		if ( is_object( $details ) && $details->spam == 1 )
-			return new WP_Error('blog_suspended', __('Blog Suspended.'));
-	}
-	return $user;
-}
-
 function wordpressmu_wp_mail_from( $email ) {
 	if ( strpos( $email, 'wordpress@' ) !== false )
 		$email = get_option( 'admin_email' );
diff --git a/wp-includes/user.php b/wp-includes/user.php
index bc84943cda..4609f0eaf3 100644
--- a/wp-includes/user.php
+++ b/wp-includes/user.php
@@ -88,8 +88,18 @@ function wp_authenticate_username_password($user, $username, $password) {
 	if ( !$userdata )
 		return new WP_Error('invalid_username', sprintf(__('<strong>ERROR</strong>: Invalid username. <a href="%s" title="Password Lost and Found">Lost your password</a>?'), site_url('wp-login.php?action=lostpassword', 'login')));
 
-	if ( is_multisite() && (1 == $userdata->spam) )
-		return new WP_Error('invalid_username', __('<strong>ERROR</strong>: Your account has been marked as a spammer.'));
+	if ( is_multisite() ) {
+		// Is user marked as spam?
+		if ( 1 == $userdata->spam)
+			return new WP_Error('invalid_username', __('<strong>ERROR</strong>: Your account has been marked as a spammer.'));
+
+		// Is a user's blog marked as spam?
+		if ( !is_super_admin( $userdata->ID ) && isset($userdata->primary_blog) ) {
+			$details = get_blog_details( $userdata->primary_blog );
+			if ( is_object( $details ) && $details->spam == 1 )
+				return new WP_Error('blog_suspended', __('Blog Suspended.'));
+		}
+	}
 
 	$userdata = apply_filters('wp_authenticate_user', $userdata, $password);
 	if ( is_wp_error($userdata) )