diff --git a/deploy/production/secret.tpl.yml b/deploy/production/secret.tpl.yml
index 5333b08a..c8f6dbdd 100644
--- a/deploy/production/secret.tpl.yml
+++ b/deploy/production/secret.tpl.yml
@@ -32,5 +32,5 @@ metadata:
   # This may be used for all justice-gov-uk environments.
   name: justice-gov-uk-alerts-slack-webhook
 type: Opaque
-data:
+stringData:
   url: "${ALERTS_SLACK_WEBHOOK}"