diff --git a/.fixtures.yml b/.fixtures.yml
index 2243fa8..07f7ea4 100644
--- a/.fixtures.yml
+++ b/.fixtures.yml
@@ -10,7 +10,7 @@ fixtures:
       ref: "3.0.2"
     stdlib:
       repo: "puppetlabs/stdlib"
-      ref: "8.1.0"
+      ref: "9.6.0"
   repositories:
     augeasproviders_core:
       repo: "https://github.com/hercules-team/augeasproviders_core.git"
diff --git a/manifests/lookup/database.pp b/manifests/lookup/database.pp
index b80a7fb..28ea393 100644
--- a/manifests/lookup/database.pp
+++ b/manifests/lookup/database.pp
@@ -57,7 +57,7 @@
     File[$path] ~> Class['postfix::service']
   }
 
-  if $ensure != 'absent' and has_key($postfix::lookup_packages, $type) {
+  if $ensure != 'absent' and $type in $postfix::lookup_packages {
     $lookup_package = $postfix::lookup_packages[$type]
     ensure_packages([$lookup_package])
     Package[$lookup_package] -> File[$path]
diff --git a/manifests/lookup/ldap.pp b/manifests/lookup/ldap.pp
index f29a9ef..acf571d 100644
--- a/manifests/lookup/ldap.pp
+++ b/manifests/lookup/ldap.pp
@@ -125,7 +125,7 @@
     content => template("${module_name}/ldap.cf.erb"),
   }
 
-  if $ensure != 'absent' and has_key($postfix::lookup_packages, 'ldap') {
+  if $ensure != 'absent' and 'ldap' in $postfix::lookup_packages {
     $ldap_package = $postfix::lookup_packages['ldap']
     ensure_packages([$ldap_package])
     Package[$ldap_package] -> File[$path]
diff --git a/manifests/lookup/memcache.pp b/manifests/lookup/memcache.pp
index 8a8b00a..e7a27d6 100644
--- a/manifests/lookup/memcache.pp
+++ b/manifests/lookup/memcache.pp
@@ -66,7 +66,7 @@
     content => template("${module_name}/memcache.cf.erb"),
   }
 
-  if $ensure != 'absent' and has_key($postfix::lookup_packages, 'memcache') {
+  if $ensure != 'absent' and 'memcache' in $postfix::lookup_packages {
     $memcache_package = $postfix::lookup_packages['memcache']
     ensure_packages([$memcache_package])
     Package[$memcache_package] -> File[$path]
diff --git a/manifests/lookup/mysql.pp b/manifests/lookup/mysql.pp
index 241d056..2c6554c 100644
--- a/manifests/lookup/mysql.pp
+++ b/manifests/lookup/mysql.pp
@@ -58,7 +58,7 @@
     content => template("${module_name}/mysql.cf.erb"),
   }
 
-  if $ensure != 'absent' and has_key($postfix::lookup_packages, 'mysql') {
+  if $ensure != 'absent' and 'mysql' in $postfix::lookup_packages {
     $mysql_package = $postfix::lookup_packages['mysql']
     ensure_packages([$mysql_package])
     Package[$mysql_package] -> File[$path]
diff --git a/manifests/lookup/pgsql.pp b/manifests/lookup/pgsql.pp
index 484a562..028d47d 100644
--- a/manifests/lookup/pgsql.pp
+++ b/manifests/lookup/pgsql.pp
@@ -44,7 +44,7 @@
     content => template("${module_name}/pgsql.cf.erb"),
   }
 
-  if $ensure != 'absent' and has_key($postfix::lookup_packages, 'pgsql') {
+  if $ensure != 'absent' and 'pgsql' in $postfix::lookup_packages {
     $pgsql_package = $postfix::lookup_packages['pgsql']
     ensure_packages([$pgsql_package])
     Package[$pgsql_package] -> File[$path]
diff --git a/manifests/lookup/sqlite.pp b/manifests/lookup/sqlite.pp
index 3e91bb2..a2b4044 100644
--- a/manifests/lookup/sqlite.pp
+++ b/manifests/lookup/sqlite.pp
@@ -36,7 +36,7 @@
     content => template("${module_name}/sqlite.cf.erb"),
   }
 
-  if $ensure != 'absent' and has_key($postfix::lookup_packages, 'sqlite') {
+  if $ensure != 'absent' and 'sqlite' in $postfix::lookup_packages {
     $sqlite_package = $postfix::lookup_packages['sqlite']
     ensure_packages([$sqlite_package])
     Package[$sqlite_package] -> File[$path]
diff --git a/metadata.json b/metadata.json
index 0be2540..5438189 100644
--- a/metadata.json
+++ b/metadata.json
@@ -10,7 +10,7 @@
   "dependencies": [
     {
       "name": "puppetlabs/stdlib",
-      "version_requirement": ">=4.13.0 <9.0.0"
+      "version_requirement": ">=4.13.0 <10.0.0"
     },
     {
       "name": "bodgit/bodgitlib",