diff --git a/lib/puppet/provider/docker_network/ruby.rb b/lib/puppet/provider/docker_network/ruby.rb
index a1bf0714..cae591ee 100644
--- a/lib/puppet/provider/docker_network/ruby.rb
+++ b/lib/puppet/provider/docker_network/ruby.rb
@@ -28,12 +28,19 @@ def network_conf
       new_flags = multi_flags.call(values, format)
       flags.concat(new_flags)
     end
-    if resource[:additional_flags].is_a?(String)
-      additional_flags = resource[:additional_flags].split
+
+    if defined?(resource[:additional_flags])
+      additional_flags = []
+      if resource[:additional_flags].is_a?(String)
+        additional_flags = resource[:additional_flags].split
+      elsif resource[:additional_flags].is_a?(Array)
+        additional_flags = resource[:additional_flags]
+      end
       additional_flags.each do |additional_flag|
         flags << additional_flag
       end
     end
+
     flags << resource[:name]
   end