diff --git a/lib/rspec-puppet/example/function_example_group.rb b/lib/rspec-puppet/example/function_example_group.rb
index 0e0b971..c907e12 100644
--- a/lib/rspec-puppet/example/function_example_group.rb
+++ b/lib/rspec-puppet/example/function_example_group.rb
@@ -6,7 +6,7 @@ module RSpec::Puppet
       function_name = self.class.top_level_description.downcase
 
       Puppet[:modulepath] = self.respond_to?(:module_path) ? module_path : RSpec.configuration.module_path
-      Puppet[:libdir] = Dir["#{Puppet[:modulepath]}/*/lib"].entries.join(':')
+      Puppet[:libdir] = Dir["#{Puppet[:modulepath]}/*/lib"].entries.join(File::PATH_SEPARATOR)
       Puppet::Parser::Functions.autoloader.loadall
 
       scope = Puppet::Parser::Scope.new