diff --git a/Gemfile.lock b/Gemfile.lock
index 7e0c0dc9..3ada0761 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,10 +1,11 @@
 PATH
   remote: .
   specs:
-    procon_bypass_man (0.3.10)
+    procon_bypass_man (0.3.11)
       action_cable_client
       blue_green_process (= 0.1.4.2)
       pbmenv (>= 0.1.11)
+      set (= 1.0.3)
       sorted_set
 
 GEM
diff --git a/lib/procon_bypass_man/version.rb b/lib/procon_bypass_man/version.rb
index 4a134a59..20469613 100644
--- a/lib/procon_bypass_man/version.rb
+++ b/lib/procon_bypass_man/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module ProconBypassMan
-  VERSION = "0.3.10"
+  VERSION = "0.3.11"
 end
diff --git a/procon_bypass_man.gemspec b/procon_bypass_man.gemspec
index 5b12c104..35a50cf6 100644
--- a/procon_bypass_man.gemspec
+++ b/procon_bypass_man.gemspec
@@ -33,6 +33,10 @@ Gem::Specification.new do |spec|
   spec.add_dependency "pbmenv", ">= 0.1.11" # enable_pbm_cloud連携機能でPbmenv.install, .cleanを使っている.
   spec.add_dependency "sorted_set"
 
+  # NOTE: https://github.com/splaplapla/procon_bypass_man/issues/275
+  # NOTE: set(1.0.4) は ruby 2.7.0以上を要求してしまう、2.5をサポートしているつもりなので1.0.3に固定しておく.
+  spec.add_dependency "set", "1.0.3"
+
   # For more information and examples about making a new gem, checkout our
   # guide at: https://bundler.io/guides/creating_gem.html
 end
diff --git a/project_template/app.rb b/project_template/app.rb
index bd962f66..469cbcde 100644
--- a/project_template/app.rb
+++ b/project_template/app.rb
@@ -12,7 +12,7 @@
   gemfile do
     source 'https://rubygems.org'
     git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
-    gem 'procon_bypass_man', '0.3.10'
+    gem 'procon_bypass_man', '0.3.11'
     # uncomment if you want to use master branch
     # gem 'procon_bypass_man', github: 'splaplapla/procon_bypass_man', branch: 'master'
     # uncomment if you want to use serial communication feature
diff --git a/project_template/app.rb.erb b/project_template/app.rb.erb
index fce8fdd0..3b46935b 100644
--- a/project_template/app.rb.erb
+++ b/project_template/app.rb.erb
@@ -12,7 +12,7 @@ begin
   gemfile do
     source 'https://rubygems.org'
     git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
-    gem 'procon_bypass_man', '0.3.10'
+    gem 'procon_bypass_man', '0.3.11'
     # uncomment if you want to use master branch
     # gem 'procon_bypass_man', github: 'splaplapla/procon_bypass_man', branch: 'master'
     # uncomment if you want to use serial communication feature