Index: src/wp-includes/user.php
===================================================================
--- src/wp-includes/user.php	(revision 31273)
+++ src/wp-includes/user.php	(working copy)
@@ -134,7 +134,7 @@
 	$user = get_user_by('login', $username);
 
 	if ( !$user )
-		return new WP_Error( 'invalid_username', sprintf( __( '<strong>ERROR</strong>: Invalid username. <a href="%s">Lost your password</a>?' ), wp_lostpassword_url() ) );
+		return new WP_Error( 'invalid_username', sprintf( __( '<strong>ERROR</strong>: Invalid username. <a href="%s">Lost your password?</a>' ), wp_lostpassword_url() ) );
 
 	/**
 	 * Filter whether the given user can be authenticated with the provided $password.
@@ -150,7 +150,7 @@
 		return $user;
 
 	if ( !wp_check_password($password, $user->user_pass, $user->ID) )
-		return new WP_Error( 'incorrect_password', sprintf( __( '<strong>ERROR</strong>: The password you entered for the username <strong>%1$s</strong> is incorrect. <a href="%2$s">Lost your password</a>?' ),
+		return new WP_Error( 'incorrect_password', sprintf( __( '<strong>ERROR</strong>: The password you entered for the username <strong>%1$s</strong> is incorrect. <a href="%2$s">Lost your password?</a>' ),
 		$username, wp_lostpassword_url() ) );
 
 	return $user;
Index: src/wp-login.php
===================================================================
--- src/wp-login.php	(revision 31273)
+++ src/wp-login.php	(working copy)
@@ -870,16 +870,18 @@
 	if ( isset($_POST['log']) )
 		$user_login = ( 'incorrect_password' == $errors->get_error_code() || 'empty_password' == $errors->get_error_code() ) ? esc_attr(wp_unslash($_POST['log'])) : '';
 	$rememberme = ! empty( $_POST['rememberme'] );
+
+	! empty( $errors->errors ) ? $aria_describedby_error = ' aria-describedby="login_error"' : $aria_describedby_error = '';
 ?>
 
 <form name="loginform" id="loginform" action="<?php echo esc_url( site_url( 'wp-login.php', 'login_post' ) ); ?>" method="post">
 	<p>
 		<label for="user_login"><?php _e('Username') ?><br />
-		<input type="text" name="log" id="user_login" class="input" value="<?php echo esc_attr($user_login); ?>" size="20" /></label>
+		<input type="text" name="log" id="user_login"<?php echo $aria_describedby_error ?> class="input" value="<?php echo esc_attr($user_login); ?>" size="20" /></label>
 	</p>
 	<p>
 		<label for="user_pass"><?php _e('Password') ?><br />
-		<input type="password" name="pwd" id="user_pass" class="input" value="" size="20" /></label>
+		<input type="password" name="pwd" id="user_pass"<?php echo $aria_describedby_error ?> class="input" value="" size="20" /></label>
 	</p>
 	<?php
 	/**