diff --git a/kubernetes/contrib/ingress-nginx-post-inst/nginx_ingress_cluster_config.yaml b/kubernetes/contrib/ingress-nginx-post-inst/nginx_ingress_cluster_config.yaml
index af0f59b..19f514f 100644
--- a/kubernetes/contrib/ingress-nginx-post-inst/nginx_ingress_cluster_config.yaml
+++ b/kubernetes/contrib/ingress-nginx-post-inst/nginx_ingress_cluster_config.yaml
@@ -11,7 +11,7 @@
 kind: ConfigMap
 apiVersion: v1
 data:
-  enable-underscores-in-headers: "on"
+  enable-underscores-in-headers: "true"
 metadata:
   name: nginx-configuration
   namespace: ingress-nginx