diff --git a/charts/controller/templates/controller-deployment.yaml b/charts/controller/templates/controller-deployment.yaml
index 6313ee652..edec5ef65 100644
--- a/charts/controller/templates/controller-deployment.yaml
+++ b/charts/controller/templates/controller-deployment.yaml
@@ -76,7 +76,7 @@ spec:
             - name: "IMAGE_PULL_POLICY"
               value: "{{ .Values.app_pull_policy }}"
             - name: "TZ"
-              value: "{{ default 'UTC' .Values.time_zone }}"
+              value: {{ .Values.time_zone | default "UTC" | quote }}
 {{- if (.Values.deploy_hook_urls) }}
             - name: DEIS_DEPLOY_HOOK_URLS
               value: "{{ .Values.deploy_hook_urls }}"