diff --git a/README.md b/README.md
index 5cff1d9..09a8ad9 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,5 @@
 # Gendered
 
-**THIS LIBRARY IS STILL IN DEVELOPMENT.**
-
 Guess the gender of names with the help of the [genderize.io](http://genderize.io).
 
 ```bash
diff --git a/Rakefile b/Rakefile
index 809eb56..26dca21 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,2 +1,10 @@
 require "bundler/gem_tasks"
 
+begin
+  require "rspec/core/rake_task"
+
+  RSpec::Core::RakeTask.new(:spec)
+
+  task :default => :spec
+rescue LoadError
+end
diff --git a/gendered.gemspec b/gendered.gemspec
index 799eeac..2403f6c 100644
--- a/gendered.gemspec
+++ b/gendered.gemspec
@@ -20,7 +20,7 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "http", ">= 0.6.2"
 
-  spec.add_development_dependency "bundler", "~> 1.6"
+  spec.add_development_dependency "bundler", "~> 2.0"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency "rspec", "~> 3.0"
 end
diff --git a/lib/gendered/guesser.rb b/lib/gendered/guesser.rb
index d315f87..8b5cf7c 100644
--- a/lib/gendered/guesser.rb
+++ b/lib/gendered/guesser.rb
@@ -23,6 +23,11 @@ def initialize(names, options = {})
 
     def guess!
       response = request(request_options)
+
+      if response["content-type"] !~ %r{\Aapplication/json\b}
+        raise GenderedError.new("received a non-JSON response with status #{response.code}: #{response.body}")
+      end
+
       update_usage(response)
       body = parse(response.body)
       case response.code
@@ -64,8 +69,8 @@ def create_names(guesses)
     def request_options
       options = {}
       options[:params] = @options.reject { |k, v| k == :connection || v.nil? }
-      options[:params]["name[]"] = @names
-      options[:connection] = @options[:connection] unless @options[:connection].empty?
+      options[:params]["name[]"] = @names.map(&:to_s)
+      options.merge!(@options[:connection]) unless @options[:connection].empty?
       options
     end
 
diff --git a/spec/lib/gendered/guesser_spec.rb b/spec/lib/gendered/guesser_spec.rb
index b8ba457..74dbd3e 100644
--- a/spec/lib/gendered/guesser_spec.rb
+++ b/spec/lib/gendered/guesser_spec.rb
@@ -58,7 +58,7 @@ module Gendered
         end
 
         it "is passed to the connection" do
-          params = hash_including(:connection => { :foo => "bar" })
+          params = hash_including(:foo => "bar")
           expect(subject).to receive(:request).with(params).and_return(fake_response)
           subject.guess!
         end
@@ -94,26 +94,33 @@ module Gendered
           expect(name).to be_a Name
         end
       end
-    end
 
-    context "with the name Evat" do
-      let :names do
-        ["Evat"]
+      context "when the response's content type is not application/json" do
+        it "raises an error" do
+          expect(subject).to receive(:request).and_return(fake_response(:content_type => "text/html"))
+          expect { subject.guess! }.to raise_error(Gendered::GenderedError, /received a non-JSON response/)
+        end
       end
 
-      it "does not error" do
-        expect{ subject.guess! }.to_not raise_error
-      end
-    end
+      context "with the name Evat" do
+        let :names do
+          ["Evat"]
+        end
 
-    context "with multiple names that are the same" do
-      let :names do
-        ["Sean","Sean"]
+        it "does not error" do
+          expect{ subject.guess! }.to_not raise_error
+        end
       end
 
-      it "guesses them both" do
-        guesses = subject.guess!
-        expect(guesses.collect(&:gender).uniq.size).to eq 1
+      context "with multiple names that are the same" do
+        let :names do
+          ["Sean","Sean"]
+        end
+
+        it "guesses them both" do
+          guesses = subject.guess!
+          expect(guesses.collect(&:gender).uniq.size).to eq 1
+        end
       end
     end
 
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 72e70d5..ba3c900 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -30,7 +30,15 @@ def fake_response(options = {})
         headers[header] = usage.include?(key) ? usage[key] : header.object_id
       end
 
-      response = double(:code => code, :body => JSON.dump(body))
+      # Must use "content-type" as that's what code checks :( But HTTP lib is case insensitive.
+      if options.include?(:content_type)
+        headers["content-type"] =  options[:content_type]
+        response = double(:code => code, :body => body.to_s)
+      else
+        headers["content-type"] = "application/json; charset=utf-8"
+        response = double(:code => code, :body => JSON.dump(body))
+      end
+
       allow(response).to receive(:[]) { |name| headers[name] }
 
       response