diff --git a/helm/monitoring/oauth2-proxy-alertmanager.yaml b/helm/monitoring/oauth2-proxy-alertmanager.yaml
index 358d05c..6937a17 100644
--- a/helm/monitoring/oauth2-proxy-alertmanager.yaml
+++ b/helm/monitoring/oauth2-proxy-alertmanager.yaml
@@ -21,6 +21,8 @@ ingress:
   className: nginx
   annotations:
     cert-manager.io/cluster-issuer: letsencrypt-prod
+    nginx.ingress.kubernetes.io/proxy-buffer-size: "16k"
+    nginx.ingress.kubernetes.io/proxy-buffers-number: "4"
   hosts:
     - alertmanager.idir-belfares.fr
   tls:
diff --git a/helm/monitoring/oauth2-proxy-prometheus.yaml b/helm/monitoring/oauth2-proxy-prometheus.yaml
index 5583e4d..ddcdb81 100644
--- a/helm/monitoring/oauth2-proxy-prometheus.yaml
+++ b/helm/monitoring/oauth2-proxy-prometheus.yaml
@@ -21,6 +21,8 @@ ingress:
   className: nginx
   annotations:
     cert-manager.io/cluster-issuer: letsencrypt-prod
+    nginx.ingress.kubernetes.io/proxy-buffer-size: "16k"
+    nginx.ingress.kubernetes.io/proxy-buffers-number: "4"
   hosts:
     - prometheus.idir-belfares.fr
   tls: