diff --git a/manifests/policy/base.pp b/manifests/policy/base.pp
index 90d6ddb1..736e220d 100644
--- a/manifests/policy/base.pp
+++ b/manifests/policy/base.pp
@@ -78,6 +78,12 @@ define openstacklib::policy::base (
         ~> Augeas<| title == "${file_path}-${key}-${value}" |>
     }
     'yaml': {
+      if stdlib::extname($file_path) == '.json' {
+        # NOTE(tkajinam): It is likely that user is not aware of migration from
+        #                 policy.json to policy.yaml
+        fail("file_path: ${file_path} should be a yaml file instead of a json file")
+      }
+
       ensure_resource('file', $file_path, {
         mode    => $file_mode,
         owner   => $file_user,
diff --git a/spec/defines/openstacklib_policy_base_spec.rb b/spec/defines/openstacklib_policy_base_spec.rb
index d1acf3d1..da8724b2 100644
--- a/spec/defines/openstacklib_policy_base_spec.rb
+++ b/spec/defines/openstacklib_policy_base_spec.rb
@@ -72,6 +72,26 @@ describe 'openstacklib::policy::base' do
       ) }
 
     end
+
+    context 'with json file_path and yaml file format' do
+      let :title do
+        'nova-contest_is_admin'
+      end
+
+      let :params do
+        {
+          :file_path   => '/etc/nova/policy.json',
+          :key         => 'context_is_admin or owner',
+          :value       => 'foo:bar',
+          :file_mode   => '0644',
+          :file_user   => 'foo',
+          :file_group  => 'bar',
+          :file_format => 'yaml',
+        }
+      end
+
+      it { should raise_error(Puppet::Error) }
+    end
   end
 
   on_supported_os({