Index: src/wp-login.php
===================================================================
--- src/wp-login.php	(revision 51064)
+++ src/wp-login.php	(working copy)
@@ -759,9 +759,13 @@
 			$user_login = wp_unslash( $_POST['user_login'] );
 		}
 
+		$action_url = network_site_url( 'wp-login.php?action=lostpassword', 'login_post' );
+		if ( ! empty( $_GET['wp_lang'] ) ) {
+			$action_url = add_query_arg( 'wp_lang', sanitize_text_field( $_GET['wp_lang'] ), $action_url );
+		}
 		?>
 
-		<form name="lostpasswordform" id="lostpasswordform" action="<?php echo esc_url( network_site_url( 'wp-login.php?action=lostpassword', 'login_post' ) ); ?>" method="post">
+		<form name="lostpasswordform" id="lostpasswordform" action="<?php echo esc_url( $action_url ); ?>" method="post">
 			<p>
 				<label for="user_login"><?php _e( 'Username or Email Address' ); ?></label>
 				<input type="text" name="user_login" id="user_login" class="input" value="<?php echo esc_attr( $user_login ); ?>" size="20" autocapitalize="off" />