diff --git a/manifests/config/kubeadm.pp b/manifests/config/kubeadm.pp
index e0de2b6c..b6a35561 100644
--- a/manifests/config/kubeadm.pp
+++ b/manifests/config/kubeadm.pp
@@ -366,8 +366,8 @@
         fail('Cannot use "cloud" as volume name')
       }
 
-      $apiserver_merged_extra_volumes = merge($apiserver_extra_volumes, $cloud_volume)
-      $controllermanager_merged_extra_volumes = merge($controllermanager_extra_volumes, $cloud_volume)
+      $apiserver_merged_extra_volumes = $apiserver_extra_volumes + $cloud_volume
+      $controllermanager_merged_extra_volumes = $controllermanager_extra_volumes + $cloud_volume
     } else {
       $apiserver_merged_extra_volumes = $apiserver_extra_volumes
       $controllermanager_merged_extra_volumes = $controllermanager_extra_volumes
@@ -381,9 +381,9 @@
   }
 
   # to_yaml emits a complete YAML document, so we must remove the leading '---'
-  $kubeadm_extra_config_yaml = regsubst(to_yaml($kubeadm_extra_config), '^---\n', '')
-  $kubelet_extra_config_yaml = regsubst(to_yaml($kubelet_extra_config), '^---\n', '')
-  $kubelet_extra_config_alpha1_yaml = regsubst(to_yaml($kubelet_extra_config_alpha1), '^---\n', '')
+  $kubeadm_extra_config_yaml = regsubst(stdlib::to_yaml($kubeadm_extra_config), '^---\n', '')
+  $kubelet_extra_config_yaml = regsubst(stdlib::to_yaml($kubelet_extra_config), '^---\n', '')
+  $kubelet_extra_config_alpha1_yaml = regsubst(stdlib::to_yaml($kubelet_extra_config_alpha1), '^---\n', '')
 
   $config_version = $kubernetes_version ? {
     /^1\.1(0|1)/              => 'v1alpha1',
diff --git a/manifests/config/worker.pp b/manifests/config/worker.pp
index 89c15921..633bab81 100644
--- a/manifests/config/worker.pp
+++ b/manifests/config/worker.pp
@@ -91,7 +91,7 @@
   Optional[Array] $skip_phases_join        = $kubernetes::skip_phases_join,
 ) {
   # to_yaml emits a complete YAML document, so we must remove the leading '---'
-  $kubelet_extra_config_yaml = regsubst(to_yaml($kubelet_extra_config), '^---\n', '')
+  $kubelet_extra_config_yaml = regsubst(stdlib::to_yaml($kubelet_extra_config), '^---\n', '')
 
   $template = $kubernetes_version ? {
     /1\.12/                  => 'v1alpha3',
diff --git a/metadata.json b/metadata.json
index e3caa574..7530f7fa 100644
--- a/metadata.json
+++ b/metadata.json
@@ -10,7 +10,7 @@
   "dependencies": [
     {
       "name": "puppetlabs-stdlib",
-      "version_requirement": ">= 4.25.0 < 10.0.0"
+      "version_requirement": ">= 9.0.0 < 10.0.0"
     },
     {
       "name": "puppetlabs-apt",