diff --git a/app/models/fluentd/agent/common.rb b/app/models/fluentd/agent/common.rb
index a0c7d6c..ca2098e 100644
--- a/app/models/fluentd/agent/common.rb
+++ b/app/models/fluentd/agent/common.rb
@@ -20,7 +20,7 @@ class Fluentd
       attr_reader :extra_options
 
       def self.included(base)
-        base.include Fluentd::Agent::ProcessOperation
+        base.send(:include, Fluentd::Agent::ProcessOperation)
       end
 
       # define these methods on each Agent class