diff --git a/manifests/policy.pp b/manifests/policy.pp
index 70aaddc..49332f0 100644
--- a/manifests/policy.pp
+++ b/manifests/policy.pp
@@ -20,12 +20,12 @@
 #   Defaults to empty hash.
 #
 # [*policy_path*]
-#   (Optional) Path to the nova policy.json file
-#   Defaults to /etc/mistral/policy.json
+#   (Optional) Path to the nova policy.yaml file
+#   Defaults to /etc/mistral/policy.yaml
 #
 class mistral::policy (
   $policies    = {},
-  $policy_path = '/etc/mistral/policy.json',
+  $policy_path = '/etc/mistral/policy.yaml',
 ) {
 
   include mistral::deps
@@ -34,9 +34,10 @@ class mistral::policy (
   validate_legacy(Hash, 'validate_hash', $policies)
 
   Openstacklib::Policy::Base {
-    file_path  => $policy_path,
-    file_user  => 'root',
-    file_group => $::mistral::params::group,
+    file_path   => $policy_path,
+    file_user   => 'root',
+    file_group  => $::mistral::params::group,
+    file_format => 'yaml',
   }
 
   create_resources('openstacklib::policy::base', $policies)
diff --git a/releasenotes/notes/migrate-policy-format-from-json-to-yaml-8a43ac1cf4d5ea54.yaml b/releasenotes/notes/migrate-policy-format-from-json-to-yaml-8a43ac1cf4d5ea54.yaml
new file mode 100644
index 0000000..fd7e1a8
--- /dev/null
+++ b/releasenotes/notes/migrate-policy-format-from-json-to-yaml-8a43ac1cf4d5ea54.yaml
@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    Now policy.yaml is used by default instead of policy.json.
diff --git a/spec/classes/mistral_policy_spec.rb b/spec/classes/mistral_policy_spec.rb
index 40e3802..f8a404a 100644
--- a/spec/classes/mistral_policy_spec.rb
+++ b/spec/classes/mistral_policy_spec.rb
@@ -5,7 +5,7 @@ describe 'mistral::policy' do
   shared_examples_for 'mistral policies' do
     let :params do
       {
-        :policy_path => '/etc/mistral/policy.json',
+        :policy_path => '/etc/mistral/policy.yaml',
         :policies    => {
           'context_is_admin' => {
             'key'   => 'context_is_admin',
@@ -17,13 +17,14 @@ describe 'mistral::policy' do
 
     it 'set up the policies' do
       is_expected.to contain_openstacklib__policy__base('context_is_admin').with({
-        :key        => 'context_is_admin',
-        :value      => 'foo:bar',
-        :file_user  => 'root',
-        :file_group => 'mistral',
+        :key         => 'context_is_admin',
+        :value       => 'foo:bar',
+        :file_user   => 'root',
+        :file_group  => 'mistral',
+        :file_format => 'yaml',
       })
       is_expected.to contain_oslo__policy('mistral_config').with(
-        :policy_file => '/etc/mistral/policy.json',
+        :policy_file => '/etc/mistral/policy.yaml',
       )
     end
   end