diff --git a/manifests/master/routes.pp b/manifests/master/routes.pp
index a5f01ee..8920610 100644
--- a/manifests/master/routes.pp
+++ b/manifests/master/routes.pp
@@ -1,44 +1,51 @@
 # Manages the routes configuration file on the master. See README.md for more
 # details.
 class puppetdb::master::routes (
   $puppet_confdir = $puppetdb::params::puppet_confdir,
   $masterless     = $puppetdb::params::masterless,
-  $routes         = {
-    'master' => {
-      'facts' => {
-        'terminus' => 'puppetdb',
-        'cache'    => 'yaml',
-      }
-    }
-  }
+  $routes         = undef,
 ) inherits puppetdb::params {
 
   if $masterless {
     $routes_real = {
       'apply' => {
         'catalog' => {
           'terminus' => 'compiler',
           'cache'    => 'puppetdb',
         },
         'facts'   => {
           'terminus' => 'facter',
           'cache'    => 'puppetdb_apply',
         }
       }
     }
-  } else {
+  } elsif $routes {
     $routes_real = $routes
+  } else {
+    if versioncmp($serverversion, '7.0') == -1 {
+      $default_fact_cache = 'yaml'
+    } else {
+      $default_fact_cache = 'json'
+    }
+    $routes_real = {
+      'master' => {
+        'facts' => {
+          'terminus' => 'puppetdb',
+          'cache'    => $default_fact_cache,
+        }
+      }
+    }
   }
 
   # TODO: this will overwrite any existing routes.yaml;
   #  to handle this properly we should just be ensuring
   #  that the proper settings exist, but to do that we'd need
   #  to parse the yaml file and rewrite it, dealing with indentation issues etc
   #  I don't think there is currently a puppet module or an augeas lens for
   #  this.
   file { "${puppet_confdir}/routes.yaml":
     ensure  => file,
     content => template('puppetdb/routes.yaml.erb'),
     mode    => '0644',
   }
 }