README.md in rdf-json-2.2.0 vs README.md in rdf-json-3.1.0

@@ -20,10 +20,10 @@
   * {RDF::JSON::Extensions}
 
 Dependencies
 ------------
 
-* [RDF.rb](http://rubygems.org/gems/rdf) (>= 1.1)
+* [RDF.rb](http://rubygems.org/gems/rdf) (~> 3.1)
 
 Installation
 ------------
 
 The recommended installation method is via [RubyGems](http://rubygems.org/).