diff --git a/infra/helm/big-reference/values.yaml b/infra/helm/big-reference/values.yaml
index 1fb687f..2ef6cda 100644
--- a/infra/helm/big-reference/values.yaml
+++ b/infra/helm/big-reference/values.yaml
@@ -286,6 +286,11 @@ workloads:
       # Only rendered with demo.otpAutofill (big.env skips empty values); off, Keycloak
       # keeps its stock theme and the mounted big-demo theme is unused.
       KC_SPI_THEME_DEFAULT: '{{ if .Values.demo.otpAutofill }}big-demo{{ end }}'
+      # Behind a TLS proxy (keycloakUrl) the dynamic backchannel URLs — token,
+      # userinfo, certs — take their scheme from the request, which reaches Keycloak
+      # as plain http; trusting X-Forwarded-Proto keeps them https so the browser
+      # doesn't block them as mixed content. In-cluster calls send no such header.
+      KC_PROXY_HEADERS: xforwarded
     ports: [{ name: http, port: 8080 }]
     # TCP, not /health/ready on the management port: nothing here gates on realm
     # import, and a wrong health path would leave the Service with no endpoints.