diff --git a/Gemfile b/Gemfile
index 8fe591e0..72196446 100644
--- a/Gemfile
+++ b/Gemfile
@@ -12,3 +12,6 @@ when 'ext', nil
 when 'pure'
   gemspec :name => 'json_pure'
 end
+
+gem "rake"
+gem "test-unit"
diff --git a/json-java.gemspec b/json-java.gemspec
index 259b908c..1ddfdc95 100644
--- a/json-java.gemspec
+++ b/json-java.gemspec
@@ -12,7 +12,7 @@ spec = Gem::Specification.new do |s|
 
   s.platform = 'java'
 
-  s.files = Dir["{docs,lib,tests}/**/*", "LICENSE"]
+  s.files = Dir["lib/**/*", "LICENSE"]
 
   s.homepage = "http://flori.github.com/json"
   s.metadata = {
@@ -25,10 +25,6 @@ spec = Gem::Specification.new do |s|
   }
 
   s.required_ruby_version = Gem::Requirement.new(">= 2.3")
-  s.test_files = ["tests/test_helper.rb"]
-
-  s.add_development_dependency "rake"
-  s.add_development_dependency "test-unit"
 end
 
 if $0 == __FILE__
diff --git a/json.gemspec b/json.gemspec
index e5ef3407..948e92c5 100644
--- a/json.gemspec
+++ b/json.gemspec
@@ -15,7 +15,6 @@ Gem::Specification.new do |s|
   s.rdoc_options = ["--title", "JSON implementation for Ruby", "--main", "README.md"]
   s.files = [
     "CHANGES.md",
-    "Gemfile",
     "LICENSE",
     "README.md",
     "VERSION",
@@ -48,13 +47,12 @@ Gem::Specification.new do |s|
     "lib/json/add/time.rb",
     "lib/json/common.rb",
     "lib/json/ext.rb",
-    "lib/json/ext/.keep",
     "lib/json/generic_object.rb",
     "lib/json/pure.rb",
     "lib/json/pure/generator.rb",
     "lib/json/pure/parser.rb",
     "lib/json/version.rb",
-  ] + Dir["tests/**/*"]
+  ]
   s.homepage = "http://flori.github.com/json"
   s.metadata = {
     'bug_tracker_uri'   => 'https://github.com/flori/json/issues',
@@ -66,8 +64,4 @@ Gem::Specification.new do |s|
   }
 
   s.required_ruby_version = Gem::Requirement.new(">= 2.3")
-  s.test_files = ["tests/test_helper.rb"]
-
-  s.add_development_dependency "rake"
-  s.add_development_dependency "test-unit"
 end
diff --git a/json_pure.gemspec b/json_pure.gemspec
index 146ef670..e6e29145 100644
--- a/json_pure.gemspec
+++ b/json_pure.gemspec
@@ -14,7 +14,6 @@ Gem::Specification.new do |s|
   s.rdoc_options = ["--title".freeze, "JSON implementation for ruby".freeze, "--main".freeze, "README.md".freeze]
   s.files = [
     "CHANGES.md".freeze,
-    "Gemfile".freeze,
     "LICENSE".freeze,
     "README.md".freeze,
     "VERSION".freeze,
@@ -36,13 +35,12 @@ Gem::Specification.new do |s|
     "lib/json/add/time.rb".freeze,
     "lib/json/common.rb".freeze,
     "lib/json/ext.rb".freeze,
-    "lib/json/ext/.keep".freeze,
     "lib/json/generic_object.rb".freeze,
     "lib/json/pure.rb".freeze,
     "lib/json/pure/generator.rb".freeze,
     "lib/json/pure/parser.rb".freeze,
     "lib/json/version.rb".freeze,
-  ] + Dir["tests/**/*"]
+  ]
   s.homepage = "http://flori.github.com/json".freeze
   s.metadata = {
     'bug_tracker_uri'   => 'https://github.com/flori/json/issues',
@@ -54,8 +52,4 @@ Gem::Specification.new do |s|
   }
 
   s.required_ruby_version = Gem::Requirement.new(">= 2.3".freeze)
-  s.test_files = ["./tests/test_helper.rb".freeze]
-
-  s.add_development_dependency "rake"
-  s.add_development_dependency "test-unit"
 end