diff --git a/README.md b/README.md
index bb04db0..7743206 100644
--- a/README.md
+++ b/README.md
@@ -47,8 +47,8 @@ helm install -f values.yaml kowl cloudhut/kowl
 | `nodeSelector` | Node selector used in deployment | `{}` |
 | `tolerations` | Tolerations for tainted nodes | `[]` |
 | `affinity` | Pod (anti)affinities | `{}` |
-| `extraVolumes` | Add additional volumes, e. g. for tls keys | `""` |
-| `extraVolumeMounts` | Add additional volumes mounts, e. g. for tls keys | `""` |
+| `extraVolumes` | Add additional volumes, e. g. for tls keys | `[]` |
+| `extraVolumeMounts` | Add additional volumes mounts, e. g. for tls keys | `[]` |
 | `extraEnv` | Additional environment variables for kowl | `""` |
 | `extraEnvFrom` | Additional environment variables for kowl mapped from Secret or ConfigMap | `""` |
 | `extraContainers` | Add additional containers, e. g. for oauth2-proxy | `{}` |
@@ -88,8 +88,6 @@ The tpl function allows us to pass string values from values.yaml through the te
 
 * extraEnv
 * extraEnvFrom
-* extraVolumes
-* extraVolumeMounts
 
 ### Kowl Config / Mounted secrets
 
diff --git a/kowl/templates/deployment.yaml b/kowl/templates/deployment.yaml
index 4a96544..6c0df62 100644
--- a/kowl/templates/deployment.yaml
+++ b/kowl/templates/deployment.yaml
@@ -36,7 +36,7 @@ spec:
           secret:
             secretName: {{ include "kowl.secretName" . }}
         {{- with .Values.extraVolumes }}
-        {{- tpl . $ | nindent 8 }}
+        {{- toYaml . | nindent 8 }}
         {{- end }}
       containers:
         - name: {{ .Chart.Name }}
@@ -67,7 +67,7 @@ spec:
               mountPath: /etc/kowl/secrets
               readOnly: true
             {{- with .Values.extraVolumeMounts }}
-            {{- tpl . $ | nindent 12 }}
+            {{- toYaml . | nindent 12 }}
             {{- end }}
           ports:
             - name: http