diff --git a/lib/addressfinder/address_autocomplete.rb b/lib/addressfinder/address_autocomplete.rb
index 61d73f2..198c25a 100644
--- a/lib/addressfinder/address_autocomplete.rb
+++ b/lib/addressfinder/address_autocomplete.rb
@@ -44,9 +44,7 @@ def encoded_params
     end
 
     def execute_request
-      request = Net::HTTP::Get.new(request_uri)
-
-      response = http.request(request)
+      response = http.request(request_uri)
 
       self.response_body = response.body
       self.response_status = response.code
diff --git a/lib/addressfinder/address_info.rb b/lib/addressfinder/address_info.rb
index 0bd5cad..4a82b85 100644
--- a/lib/addressfinder/address_info.rb
+++ b/lib/addressfinder/address_info.rb
@@ -37,9 +37,7 @@ def encoded_params
     end
 
     def execute_request
-      request = Net::HTTP::Get.new(request_uri)
-
-      response = http.request(request)
+      response = http.request(request_uri)
 
       self.response_body = response.body
       self.response_status = response.code
diff --git a/lib/addressfinder/address_search.rb b/lib/addressfinder/address_search.rb
index 540fdc5..685af80 100644
--- a/lib/addressfinder/address_search.rb
+++ b/lib/addressfinder/address_search.rb
@@ -37,9 +37,7 @@ def encoded_params
     end
 
     def execute_request
-      request = Net::HTTP::Get.new(request_uri)
-
-      response = http.request(request)
+      response = http.request(request_uri)
 
       self.response_body = response.body
       self.response_status = response.code
diff --git a/lib/addressfinder/configuration.rb b/lib/addressfinder/configuration.rb
index 0e683f7..015bd1f 100644
--- a/lib/addressfinder/configuration.rb
+++ b/lib/addressfinder/configuration.rb
@@ -14,6 +14,7 @@ class Configuration
     attr_accessor :domain
     attr_accessor :retries
     attr_accessor :retry_delay
+    attr_accessor :ca
 
     def initialize
       self.hostname = 'api.addressfinder.io'
@@ -23,6 +24,7 @@ def initialize
       self.retry_delay = 5
       self.default_country = 'nz'
       self.verification_version = 'v1'
+      self.ca = "Ruby/#{AddressFinder::VERSION}"
     end
   end
 end
diff --git a/lib/addressfinder/http.rb b/lib/addressfinder/http.rb
index e6a9623..c53eb3a 100644
--- a/lib/addressfinder/http.rb
+++ b/lib/addressfinder/http.rb
@@ -15,11 +15,15 @@ def start(&block)
       end
     end
 
-    def request(args)
+    def request(request_uri)
       retries = 0
       begin
         re_establish_connection if @connection_is_bad
-        net_http.request(args)
+
+        uri = build_uri(request_uri)
+        request = Net::HTTP::Get.new(uri)
+
+        net_http.request(request)
       rescue Net::ReadTimeout, Net::OpenTimeout, SocketError => error
         if retries < config.retries
           retries += 1
@@ -40,6 +44,19 @@ def re_establish_connection
       net_http.start
     end
 
+    def build_uri(request_uri)
+      uri = URI(request_uri)
+      encoded_ca = URI.encode_www_form_component(config.ca)
+
+      if uri.query
+        uri.query += "&ca=#{encoded_ca}"
+      else
+        uri.query = "ca=#{encoded_ca}"
+      end
+
+      uri.to_s
+    end
+
     def net_http
       @net_http ||= begin
         http = Net::HTTP.new(config.hostname, config.port, config.proxy_host,
diff --git a/lib/addressfinder/location_info.rb b/lib/addressfinder/location_info.rb
index 6737acc..2356aab 100644
--- a/lib/addressfinder/location_info.rb
+++ b/lib/addressfinder/location_info.rb
@@ -38,9 +38,7 @@ def encoded_params
     end
 
     def execute_request
-      request = Net::HTTP::Get.new(request_uri)
-
-      response = http.request(request)
+      response = http.request(request_uri)
 
       self.response_body = response.body
       self.response_status = response.code
diff --git a/lib/addressfinder/location_search.rb b/lib/addressfinder/location_search.rb
index ad74001..8972be7 100644
--- a/lib/addressfinder/location_search.rb
+++ b/lib/addressfinder/location_search.rb
@@ -38,9 +38,7 @@ def encoded_params
     end
 
     def execute_request
-      request = Net::HTTP::Get.new(request_uri)
-
-      response = http.request(request)
+      response = http.request(request_uri)
 
       self.response_body = response.body
       self.response_status = response.code
diff --git a/lib/addressfinder/v1/base.rb b/lib/addressfinder/v1/base.rb
index 1db30e4..19f970d 100644
--- a/lib/addressfinder/v1/base.rb
+++ b/lib/addressfinder/v1/base.rb
@@ -20,12 +20,12 @@ def perform
         build_request
         execute_request
         build_result
-  
+
         self
       end
 
       private
-  
+
       attr_reader :request_uri, :params, :http, :path
       attr_accessor :response_body, :response_status
       attr_writer :result
@@ -33,20 +33,18 @@ def perform
       def build_request
         @request_uri = "#{path}?#{encoded_params}"
       end
-  
+
       def encoded_params
         Util.encode_and_join_params(params)
       end
-  
+
       def execute_request
-        request = Net::HTTP::Get.new(request_uri)
-  
-        response = http.request(request)
-  
+        response = http.request(request_uri)
+
         self.response_body = response.body
         self.response_status = response.code
       end
-  
+
       def build_result
         case response_status
         when '200'
@@ -55,15 +53,15 @@ def build_result
           raise AddressFinder::RequestRejectedError.new(response_status, response_body)
         end
       end
-  
+
       def response_hash
         @_response_hash ||= MultiJson.load(response_body)
       end
-  
+
       def config
         @_config ||= AddressFinder.configuration
       end
-  
+
       class Result < OpenStruct
       end
     end
diff --git a/lib/addressfinder/v2/au/verification.rb b/lib/addressfinder/v2/au/verification.rb
index 3649a1c..b1c9429 100644
--- a/lib/addressfinder/v2/au/verification.rb
+++ b/lib/addressfinder/v2/au/verification.rb
@@ -56,9 +56,7 @@ def build_request
         end
 
         def execute_request
-          request = Net::HTTP::Get.new(request_uri)
-
-          response = http.request(request)
+          response = http.request(request_uri)
 
           self.response_body = response.body
           self.response_status = response.code
diff --git a/lib/addressfinder/verification.rb b/lib/addressfinder/verification.rb
index 07e56da..381c4ee 100644
--- a/lib/addressfinder/verification.rb
+++ b/lib/addressfinder/verification.rb
@@ -61,9 +61,7 @@ def build_request
     end
 
     def execute_request
-      request = Net::HTTP::Get.new(request_uri)
-
-      response = http.request(request)
+      response = http.request(request_uri)
 
       self.response_body = response.body
       self.response_status = response.code
diff --git a/spec/lib/addressfinder/configuration_spec.rb b/spec/lib/addressfinder/configuration_spec.rb
new file mode 100644
index 0000000..b6ff52f
--- /dev/null
+++ b/spec/lib/addressfinder/configuration_spec.rb
@@ -0,0 +1,8 @@
+require 'spec_helper'
+
+RSpec.describe AddressFinder::Configuration do
+  it 'sets the client agent with the gem version' do
+    config = AddressFinder::Configuration.new
+    expect(config.ca).to eq("Ruby/#{AddressFinder::VERSION}")
+  end
+end
\ No newline at end of file
diff --git a/spec/lib/addressfinder/http_spec.rb b/spec/lib/addressfinder/http_spec.rb
new file mode 100644
index 0000000..3960171
--- /dev/null
+++ b/spec/lib/addressfinder/http_spec.rb
@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+RSpec.describe AddressFinder::HTTP do
+  let(:config) { AddressFinder::Configuration.new }
+  let(:http) { described_class.new(config) }
+  let(:request_uri) { "https://api.addressfinder.io?param=value" }
+
+  describe '#build_uri' do
+    it 'appends the ca parameter to the query string' do
+      uri_with_ca = http.send(:build_uri, request_uri)
+      expect(uri_with_ca).to include("ca=Ruby%2F#{AddressFinder::VERSION}")
+    end
+
+    it 'preserves existing query parameters' do
+      uri_with_ca = http.send(:build_uri, request_uri)
+      expect(uri_with_ca).to include("param=value")
+    end
+  end
+end
diff --git a/spec/lib/addressfinder_spec.rb b/spec/lib/addressfinder_spec.rb
index 25c4572..be4d634 100644
--- a/spec/lib/addressfinder_spec.rb
+++ b/spec/lib/addressfinder_spec.rb
@@ -31,7 +31,8 @@
       end
 
       it "safely passes arguments through" do
-        stub_request(:get, Addressable::Template.new("https://api.addressfinder.io/api/nz/address/verification{?args*}")).to_return(:status => 200, :body => "{}", :headers => {})
+        nz_verification_endpoint = "https://api.addressfinder.io/api/nz/address/verification"
+        stub_request(:get, /\A#{nz_verification_endpoint}/).to_return(:status => 200, :body => "{}", :headers => {})
         subject
       end
     end
@@ -44,7 +45,8 @@
       end
 
       it "safely passes arguments through" do
-        stub_request(:get, Addressable::Template.new("https://api.addressfinder.io/api/au/address/v2/verification{?args*}")).to_return(:status => 200, :body => "{}", :headers => {})
+        au_verification_endpoint = "https://api.addressfinder.io/api/au/address/v2/verification"
+        stub_request(:get, /\A#{au_verification_endpoint}/).to_return(:status => 200, :body => "{}", :headers => {})
         subject
       end
     end