diff --git a/.rspec b/.rspec
index 16f9cdb0..b83d9b7a 100644
--- a/.rspec
+++ b/.rspec
@@ -1,2 +1,3 @@
 --color
 --format documentation
+--require spec_helper
diff --git a/lib/pact_broker/client/versions.rb b/lib/pact_broker/client/versions.rb
index 40a2a3aa..02097d99 100644
--- a/lib/pact_broker/client/versions.rb
+++ b/lib/pact_broker/client/versions.rb
@@ -1,4 +1,5 @@
 require_relative 'base_client'
+require 'pact_broker/client/pacts'
 
 module PactBroker
   module Client
@@ -38,7 +39,7 @@ def pacts
       private
 
       def tag_url options
-        "#{version_base_url(options)}/tags/#{options.fetch(:tag)}"
+        "#{version_base_url(options)}/tags/#{encode_param(options.fetch(:tag))}"
       end
 
       def versions_base_url options
diff --git a/pact-broker-client.gemspec b/pact-broker-client.gemspec
index bf258f79..647f487d 100644
--- a/pact-broker-client.gemspec
+++ b/pact-broker-client.gemspec
@@ -30,4 +30,5 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency 'fakefs', '~> 0.4'
   gem.add_development_dependency 'rspec-fire'
   gem.add_development_dependency 'appraisal'
+  gem.add_development_dependency 'webmock', '~> 3.0'
 end
diff --git a/spec/lib/pact_broker/client/versions_spec.rb b/spec/lib/pact_broker/client/versions_spec.rb
index bae609bd..681fe159 100644
--- a/spec/lib/pact_broker/client/versions_spec.rb
+++ b/spec/lib/pact_broker/client/versions_spec.rb
@@ -5,12 +5,28 @@ module Client
       let(:client_options) do
         { some_option: 'option value'}
       end
-      let(:base_url) { 'https://blah' }
+      let(:base_url) { 'http://blah' }
+      let(:pacticipant_name) { 'Foo' }
+      let(:version_number) { '1.2.3' }
+
+      subject { Versions.new(base_url: base_url, client_options: client_options) }
 
       describe 'pacts' do
         it 'initializes versions with base url and client options' do
           expect(PactBroker::Client::Pacts).to receive(:new).with(base_url: base_url, client_options: client_options)
-          Versions.new(base_url: base_url, client_options: client_options).pacts
+          subject.pacts
+        end
+      end
+
+      describe 'tag' do
+        context "when the tag has a / in it" do
+          let(:tag) { 'feat/foo' }
+          let!(:request) { stub_request(:put, "http://blah/pacticipants/Foo/versions/1.2.3/tags/feat%2Ffoo").to_return(status: 200) }
+
+          it "URL encodes the /" do
+            subject.tag(pacticipant: pacticipant_name, version: version_number, tag: tag)
+            expect(request).to have_been_made
+          end
         end
       end
     end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index cef584ef..6553b688 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,4 +1,7 @@
 require 'rspec/fire'
+require 'webmock/rspec'
+
+WebMock.disable_net_connect!(allow_localhost: true)
 
 RSpec.configure do | config |
   config.include RSpec::Fire