diff --git a/src/Composer/Command/DiagnoseCommand.php b/src/Composer/Command/DiagnoseCommand.php
index 3efb34973..11d1e1aa0 100644
--- a/src/Composer/Command/DiagnoseCommand.php
+++ b/src/Composer/Command/DiagnoseCommand.php
@@ -121,8 +121,8 @@ EOT
$rate = $this->getGithubRateLimit('github.com');
$this->outputResult(true);
if (10 > $rate['remaining']) {
- $io->write('WARNING');
- $io->write(sprintf(
+ $io->writeError('WARNING');
+ $io->writeError(sprintf(
'Github has a rate limit on their API. '
. 'You currently have %u '
. 'out of %u requests left.' . PHP_EOL