Specify fully qualified variable properly

manifests/init.pp

@@ -12,7 +12,7 @@ class freeradius (
   $syslog          = false,
 ) inherits freeradius::params {
 
-  if ($::fr_version != 3) {
+  if ($freeradius::fr_version != 3) {
     fail('This module is only compatible with FreeRADIUS 3')
   }