diff --git a/VERSION b/VERSION
index ccbccc3..c043eea 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.2.0
+2.2.1
diff --git a/rdf-aggregate-repo.gemspec b/rdf-aggregate-repo.gemspec
index 8800601..0758206 100755
--- a/rdf-aggregate-repo.gemspec
+++ b/rdf-aggregate-repo.gemspec
@@ -23,12 +23,15 @@ Gem::Specification.new do |gem|
 
   gem.required_ruby_version      = '>= 2.2.2'
   gem.requirements               = []
-  gem.add_runtime_dependency     'rdf',         '~> 2.0'
-  gem.add_development_dependency 'rdf-spec',    '~> 2.0'
-  gem.add_development_dependency 'rdf-turtle',  '~> 2.0'
-  gem.add_development_dependency 'rspec',       '~> 3.2'
-  gem.add_development_dependency 'rspec-its',   '~> 1.0'
-  gem.add_development_dependency 'yard',        '~> 0.8'
+  #gem.add_runtime_dependency     'rdf',         '~> 3.0'
+  #gem.add_development_dependency 'rdf-spec',    '~> 3.0'
+  #gem.add_development_dependency 'rdf-turtle',  '~> 3.0'
+  gem.add_runtime_dependency     'rdf',         '>= 2.2', '< 4.0'
+  gem.add_development_dependency 'rdf-spec',    '>= 2.2', '< 4.0'
+  gem.add_development_dependency 'rdf-turtle',  '>= 2.2', '< 4.0'
+  gem.add_development_dependency 'rspec',       '~> 3.7'
+  gem.add_development_dependency 'rspec-its',   '~> 1.2'
+  gem.add_development_dependency 'yard',        '~> 0.9'
 
   gem.post_install_message       = nil
 end