diff --git a/src/main/cljc/dda/c4k_nextcloud/core.cljc b/src/main/cljc/dda/c4k_nextcloud/core.cljc
index 20b57e2..928c879 100644
--- a/src/main/cljc/dda/c4k_nextcloud/core.cljc
+++ b/src/main/cljc/dda/c4k_nextcloud/core.cljc
@@ -9,7 +9,7 @@
   [dda.c4k-nextcloud.nextcloud :as nextcloud]
   [dda.c4k-nextcloud.backup :as backup]))
 
-(def config-defaults {:issuer :staging})
+(def config-defaults {:issuer "staging"})
 
 (def auth? (s/keys :req-un [::postgres/postgres-db-user ::postgres/postgres-db-password
                             ::nextcloud/nextcloud-admin-user ::nextcloud/nextcloud-admin-password
diff --git a/src/main/cljc/dda/c4k_nextcloud/nextcloud.cljc b/src/main/cljc/dda/c4k_nextcloud/nextcloud.cljc
index ac3db50..df5c85f 100644
--- a/src/main/cljc/dda/c4k_nextcloud/nextcloud.cljc
+++ b/src/main/cljc/dda/c4k_nextcloud/nextcloud.cljc
@@ -10,8 +10,14 @@
   [dda.c4k-common.common :as cm]
   [dda.c4k-common.postgres :as postgres]))
 
+; TODO: Replace method in c4k-common.predicate and update all c4k modules.
+(defn letsencrypt-issuer?
+  [input]
+  (contains? #{"prod" "staging"} input))
+; TODO: Remove (name ...) function calls, when issuer is no longer a keyword (also in c4k-common)
+
 (s/def ::fqdn cp/fqdn-string?)
-(s/def ::issuer cp/letsencrypt-issuer?)
+(s/def ::issuer letsencrypt-issuer?) ;cp/letsencrypt-issuer?
 (s/def ::restic-repository string?)
 (s/def ::nextcloud-data-volume-path string?)
 (s/def ::nextcloud-admin-user cp/bash-env-string?)
@@ -52,7 +58,7 @@
 
 (defn generate-ingress [config]
   (let [{:keys [fqdn issuer]
-         :or {issuer :staging}} config
+         :or {issuer "staging"}} config
         letsencrypt-issuer (name issuer)]
     (->
      (yaml/from-string (yaml/load-resource "nextcloud/ingress.yaml"))
diff --git a/src/test/cljc/dda/c4k_nextcloud/core_test.cljc b/src/test/cljc/dda/c4k_nextcloud/core_test.cljc
index f46cfe6..82cfcf5 100644
--- a/src/test/cljc/dda/c4k_nextcloud/core_test.cljc
+++ b/src/test/cljc/dda/c4k_nextcloud/core_test.cljc
@@ -13,7 +13,7 @@
                                   :postgres-db-password "nextcloud-db-password"
                                   :nextcloud-admin-user "cloudadmin"
                                   :nextcloud-admin-password "cloudpassword"
-                                  :issuer :prod
+                                  :issuer "prod"
                                   :nextcloud-data-volume-path "/var/nextcloud"
                                   :postgres-data-volume-path "/var/postgres"
                                   :aws-access-key-id "aws-id"
@@ -26,7 +26,7 @@
                                   :postgres-db-password "nextcloud-db-password"
                                   :nextcloud-admin-user "cloudadmin"
                                   :nextcloud-admin-password "cloudpassword"
-                                  :issuer :prod
+                                  :issuer "prod"
                                   :aws-access-key-id "aws-id"
                                   :aws-secret-access-key "aws-secret"
                                   :restic-password "restic-pw"
@@ -37,7 +37,7 @@
                                   :postgres-db-password "nextcloud-db-password"
                                   :nextcloud-admin-user "cloudadmin"
                                   :nextcloud-admin-password "cloudpassword"
-                                  :issuer :prod
+                                  :issuer "prod"
                                   :aws-access-key-id "aws-id"
                                   :aws-secret-access-key "aws-secret"
                                   :restic-password "restic-pw"}))))
@@ -47,7 +47,7 @@
                                  :postgres-db-password "nextcloud-db-password"
                                  :nextcloud-admin-user "cloudadmin"
                                  :nextcloud-admin-password "cloudpassword"
-                                 :issuer :prod
+                                 :issuer "prod"
                                  :aws-access-key-id "aws-id"
                                  :aws-secret-access-key "aws-secret"
                                  :restic-password "restic-pw"})
@@ -59,7 +59,7 @@
                                  :postgres-db-password "nextcloud-db-password"
                                  :nextcloud-admin-user "cloudadmin"
                                  :nextcloud-admin-password "cloudpassword"
-                                 :issuer :prod
+                                 :issuer "prod"
                                  :aws-access-key-id "aws-id"
                                  :aws-secret-access-key "aws-secret"
                                  :restic-password "restic-pw"})
diff --git a/src/test/cljc/dda/c4k_nextcloud/nextcloud_test.cljc b/src/test/cljc/dda/c4k_nextcloud/nextcloud_test.cljc
index 024a0c6..3a2b6b6 100644
--- a/src/test/cljc/dda/c4k_nextcloud/nextcloud_test.cljc
+++ b/src/test/cljc/dda/c4k_nextcloud/nextcloud_test.cljc
@@ -25,7 +25,7 @@
            :dnsNames ["xx"]
            :issuerRef
            {:name "prod", :kind "ClusterIssuer"}}}
-         (cut/generate-certificate {:fqdn "xx" :issuer :prod}))))
+         (cut/generate-certificate {:fqdn "xx" :issuer "prod"}))))
 
 (deftest should-generate-ingress
   (is (= {:apiVersion "networking.k8s.io/v1"
diff --git a/valid-config.edn b/valid-config.edn
index 87ebb80..b50ced9 100644
--- a/valid-config.edn
+++ b/valid-config.edn
@@ -1,5 +1,5 @@
 {:fqdn "cloud.test.meissa-gmbh.de"
- :issuer :staging
+ :issuer "staging"
  :nextcloud-data-volume-path "/var/cloud"
  :postgres-data-volume-path "/var/postgres"
  :restic-repository "s3:s3.amazonaws.com/your-bucket/your-folder"}
\ No newline at end of file
diff --git a/valid-config.yaml b/valid-config.yaml
index dff692c..c716cf2 100644
--- a/valid-config.yaml
+++ b/valid-config.yaml
@@ -1,5 +1,5 @@
 fqdn: "cloud.test.meissa-gmbh.de"
-issuer: :staging
+issuer: "staging"
 nextcloud-data-volume-path: "/var/cloud"
 postgres-data-volume-path: "/var/postgres"
 restic-repository: "s3:s3.amazonaws.com/your-bucket/your-folder"
\ No newline at end of file