diff --git a/lib/pact_broker/api/resources/matrix.rb b/lib/pact_broker/api/resources/matrix.rb
index ca0c48c49..f82522ea0 100644
--- a/lib/pact_broker/api/resources/matrix.rb
+++ b/lib/pact_broker/api/resources/matrix.rb
@@ -1,6 +1,6 @@
 require 'pact_broker/api/resources/base_resource'
 require 'pact_broker/api/decorators/matrix_decorator'
-require 'cgi'
+require 'pact_broker/matrix/parse_query'
 
 module PactBroker
   module Api
@@ -16,7 +16,7 @@ def allowed_methods
         end
 
         def malformed_request?
-          error_messages = matrix_service.validate_selectors(selectors)
+          error_messages = matrix_service.validate_selectors(criteria)
           if error_messages.any?
             set_json_validation_error_messages error_messages
             true
@@ -26,21 +26,12 @@ def malformed_request?
         end
 
         def to_json
-          criteria = selected_versions.each_with_object({}) { | version, hash | hash[version.pacticipant.name] = version.number }
           lines = matrix_service.find(criteria)
           PactBroker::Api::Decorators::MatrixPactDecorator.new(lines).to_json(user_options: { base_url: base_url })
         end
 
-        def selectors
-          @selectors ||= CGI.parse(CGI.unescape(request.uri.query))['selectors[]']
-        end
-
-        def version_selectors
-          @version_selectors ||= selectors.select{ | selector| selector.include?("/version/") }
-        end
-
-        def selected_versions
-          @selected_versions ||= version_service.find_versions_by_selector(version_selectors)
+        def criteria
+          @criteria ||= PactBroker::Matrix::ParseQuery.call(request.uri.query)
         end
       end
     end
diff --git a/lib/pact_broker/matrix/parse_query.rb b/lib/pact_broker/matrix/parse_query.rb
new file mode 100644
index 000000000..8992f92a1
--- /dev/null
+++ b/lib/pact_broker/matrix/parse_query.rb
@@ -0,0 +1,14 @@
+require 'cgi'
+
+module PactBroker
+  module Matrix
+    class ParseQuery
+      def self.call query
+        params = CGI.parse(CGI.unescape(query))
+        params['pacticipant[]'].zip(params['version[]']).each_with_object({}) do | (pacticipant, version), hash |
+          hash[pacticipant] = version
+        end
+      end
+    end
+  end
+end
diff --git a/lib/pact_broker/matrix/service.rb b/lib/pact_broker/matrix/service.rb
index f95dab487..9d4364ec6 100644
--- a/lib/pact_broker/matrix/service.rb
+++ b/lib/pact_broker/matrix/service.rb
@@ -3,7 +3,6 @@
 module PactBroker
   module Matrix
     module Service
-      VERSION_SELECTOR_PATTERN = %r{(^[^/]+)/version/[^/]+$}.freeze
 
       extend self
       extend PactBroker::Repositories
@@ -23,27 +22,17 @@ def find_compatible_pacticipant_versions criteria
 
       def validate_selectors selectors
         error_messages = []
-        selectors.each do | version_selector |
-          if !(version_selector =~ VERSION_SELECTOR_PATTERN)
-            error_messages << "Invalid version selector '#{version_selector}'. Format must be <pacticipant_name>/version/<version>"
-          end
-        end
 
-        selectors.each do | version_selector |
-          if match = version_selector.match(VERSION_SELECTOR_PATTERN)
-            pacticipant_name = match[1]
-            unless pacticipant_service.find_pacticipant_by_name(pacticipant_name)
-              error_messages << "Pacticipant '#{pacticipant_name}' not found"
-            end
+        selectors.keys.each do | pacticipant_name |
+          unless pacticipant_service.find_pacticipant_by_name(pacticipant_name)
+            error_messages << "Pacticipant '#{pacticipant_name}' not found"
           end
         end
 
         if error_messages.empty?
-          selected_versions = version_service.find_versions_by_selector(selectors)
-          if selected_versions.any?(&:nil?)
-            selected_versions.each_with_index do | selected_version, i |
-              error_messages << "No pact or verification found for #{selectors[i]}" if selected_version.nil?
-            end
+          selectors.each do | pacticipant_name, version_number |
+            version = version_service.find_by_pacticipant_name_and_number(pacticipant_name: pacticipant_name, pacticipant_version_number: version_number)
+            error_messages << "No pact or verification found for #{pacticipant_name} version #{version_number}" if version.nil?
           end
         end
 
diff --git a/script/seed-matrix.rb b/script/seed-matrix.rb
new file mode 100755
index 000000000..1da8cfe96
--- /dev/null
+++ b/script/seed-matrix.rb
@@ -0,0 +1,71 @@
+#!/usr/bin/env ruby
+
+raise "Please supply database path" unless ARGV[0]
+
+$LOAD_PATH.unshift './lib'
+$LOAD_PATH.unshift './spec'
+ENV['RACK_ENV'] = 'development'
+require 'sequel'
+require 'logger'
+DATABASE_CREDENTIALS = {logger: Logger.new($stdout), adapter: "sqlite", database: ARGV[0], :encoding => 'utf8'}
+connection = Sequel.connect(DATABASE_CREDENTIALS)
+connection.timezone = :utc
+require 'pact_broker/db'
+PactBroker::DB.connection = connection
+require 'pact_broker'
+require 'support/test_data_builder'
+
+
+tables_to_clean = [:labels, :webhook_executions, :triggered_webhooks, :verifications, :pact_publications, :pact_versions, :pacts, :pact_version_contents, :tags, :versions, :webhook_headers, :webhooks, :pacticipants]
+
+tables_to_clean.each do | table_name |
+  connection[table_name].delete if connection.table_exists?(table_name)
+end
+
+=begin
+
+A -> B ->  C
+
+1  s  1  f   1
+
+      2   s  2
+
+=end
+
+# TestDataBuilder.new.create_pact_with_hierarchy("A", "1.2.3", "B")
+#               .use_provider("B")
+#               .create_version("2.0.0")
+#               .create_provider("C")
+#               .create_version("3.0.0")
+#               .create_pact
+
+TestDataBuilder.new
+  .create_pact_with_hierarchy("A", "1", "B")
+  .create_verification(provider_version: '1')
+  .create_verification(provider_version: '2', number: 2, success: false)
+  .create_verification(provider_version: '4', number: 3)
+  .create_provider_version("5")
+  .use_consumer("B")
+  .use_consumer_version("1")
+  .create_provider("C")
+  .create_pact
+  .create_verification(provider_version: '1', success: false)
+  .use_consumer_version("2")
+  .create_pact
+  .create_verification(provider_version: '2', success: true)
+  .create_consumer_version("3")
+  .create_pact
+  .create_pact_with_hierarchy("the-example-application", "391c43cae8c0e83c570c191f7324fccd67e53abc", "another-example-application")
+  .create_verification(provider_version: '391c43cae8c0e83c570c191f7324fccd67e53abc')
+  .create_verification(provider_version: '57fa24e44efc4d8aa42bb855a8217f145b5b1b5b', number: 2, success: false)
+  .create_verification(provider_version: '4', number: 3)
+  .use_consumer("another-example-application")
+  .use_consumer_version("391c43cae8c0e83c570c191f7324fccd67e53abc")
+  .create_provider("a-third-example-application")
+  .create_pact
+  .create_verification(provider_version: '391c43cae8c0e83c570c191f7324fccd67e53abc', success: false)
+  .use_consumer_version("57fa24e44efc4d8aa42bb855a8217f145b5b1b5b")
+  .create_pact
+  .create_verification(provider_version: '57fa24e44efc4d8aa42bb855a8217f145b5b1b5b', success: true)
+
+
diff --git a/spec/features/get_matrix_spec.rb b/spec/features/get_matrix_spec.rb
index a4e140e10..8d430aa72 100644
--- a/spec/features/get_matrix_spec.rb
+++ b/spec/features/get_matrix_spec.rb
@@ -10,7 +10,8 @@
   let(:path) { "/matrix" }
   let(:params) do
     {
-      selectors: ['Consumer/version/1.0.0','Provider/version/4.5.6']
+      pacticipant: ['Consumer', 'Provider'],
+      version: ['1.0.0', '4.5.6']
     }
   end
   let(:last_response_body) { JSON.parse(subject.body, symbolize_names: true) }
diff --git a/spec/lib/pact_broker/api/resources/matrix_spec.rb b/spec/lib/pact_broker/api/resources/matrix_spec.rb
index 54d93f87c..13cb35e49 100644
--- a/spec/lib/pact_broker/api/resources/matrix_spec.rb
+++ b/spec/lib/pact_broker/api/resources/matrix_spec.rb
@@ -12,13 +12,13 @@ module Resources
         let(:td) { TestDataBuilder.new }
         let(:path) { "/matrix" }
         let(:json_response_body) { JSON.parse(subject.body, symbolize_names: true) }
-        let(:params) { { selectors: ['Foo/version/1', 'Bar/version/2'] } }
+        let(:params) { { pacticipant: ['Foo', 'Bar'], version: ['1', '2'] } }
         let(:error_messages) { [] }
 
         subject { get path, params, {'Content-Type' => 'application/hal+json'}; last_response }
 
         it "validates the selectors" do
-          expect(PactBroker::Matrix::Service).to receive(:validate_selectors).with(['Foo/version/1', 'Bar/version/2'])
+          expect(PactBroker::Matrix::Service).to receive(:validate_selectors).with('Foo' => '1', 'Bar' => '2')
           subject
         end
 
diff --git a/spec/lib/pact_broker/matrix/parse_query_spec.rb b/spec/lib/pact_broker/matrix/parse_query_spec.rb
new file mode 100644
index 000000000..a5039aafd
--- /dev/null
+++ b/spec/lib/pact_broker/matrix/parse_query_spec.rb
@@ -0,0 +1,25 @@
+require 'pact_broker/matrix/parse_query'
+
+module PactBroker
+  module Matrix
+    describe ParseQuery do
+      describe ".call" do
+        let(:query) { "pacticipant[]=Foo&pacticipant[]=Bar&version[]=1.2.3&version[]=9.9.9" }
+
+        subject { ParseQuery.call(query) }
+
+        it "extracts the pacticipant names and respective versions" do
+          expect(subject).to eq "Foo" => "1.2.3", "Bar" => "9.9.9"
+        end
+
+        context "with spaces" do
+          let(:query) { "pacticipant%5B%5D=Name%20With%20Spaces&version%5B%5D=1%202" }
+
+          it "works" do
+            expect(subject).to eq "Name With Spaces" => "1 2"
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/spec/lib/pact_broker/matrix/service_spec.rb b/spec/lib/pact_broker/matrix/service_spec.rb
index 23bfa220e..5cf997361 100644
--- a/spec/lib/pact_broker/matrix/service_spec.rb
+++ b/spec/lib/pact_broker/matrix/service_spec.rb
@@ -9,13 +9,6 @@ module Matrix
 
         subject { Service.validate_selectors(selectors) }
 
-        context "when a selector format is invalid" do
-          let(:selectors) { ["Foo/1"] }
-
-          it "returns error messages" do
-            expect(subject.first).to eq "Invalid version selector 'Foo/1'. Format must be <pacticipant_name>/version/<version>"
-          end
-        end
 
         context "when there is only one selector" do
           before do
@@ -23,7 +16,7 @@ module Matrix
               .create_version("1")
           end
 
-          let(:selectors) { ["Foo/version/1"] }
+          let(:selectors) { {"Foo" => "1"} }
 
           it "returns error messages" do
             expect(subject.first).to eq "Please provide 2 or more version selectors."
@@ -39,15 +32,15 @@ module Matrix
 
           end
 
-          let(:selectors) { ["Foo/version/1", "Bar/version/1"] }
+          let(:selectors) { {"Foo" => "1", "Bar" => "1"} }
 
           it "returns error messages" do
-            expect(subject).to eq ["No pact or verification found for Bar/version/1"]
+            expect(subject).to eq ["No pact or verification found for Bar version 1"]
           end
         end
 
         context "when the pacticipant does not exist" do
-          let(:selectors) { ["Foo/version/1"] }
+          let(:selectors) { {"Foo" => "1"} }
 
           it "returns error messages" do
             expect(subject.first).to eq "Pacticipant 'Foo' not found"
diff --git a/spec/service_consumers/provider_states_for_pact_broker_client.rb b/spec/service_consumers/provider_states_for_pact_broker_client.rb
index 57f9c51f6..b09fd0a58 100644
--- a/spec/service_consumers/provider_states_for_pact_broker_client.rb
+++ b/spec/service_consumers/provider_states_for_pact_broker_client.rb
@@ -2,6 +2,18 @@
 
 Pact.provider_states_for "Pact Broker Client" do
 
+  provider_state "the pact for Foo Thing version 1.2.3 has been verified by Bar version 4.5.6" do
+    set_up do
+      TestDataBuilder.new
+        .create_pact_with_hierarchy("Foo Thing", "1.2.3", "Bar")
+        .create_verification(provider_version: "4.5.6")
+        .create_verification(provider_version: "7.8.9", number: 2)
+        .create_consumer_version("2.0.0")
+        .create_pact
+        .create_verification(provider_version: "4.5.6")
+    end
+  end
+
   provider_state "the pact for Foo version 1.2.3 has been verified by Bar version 4.5.6" do
     set_up do
       TestDataBuilder.new