diff --git a/app/models/service_sorter.rb b/app/models/service_sorter.rb
index a6ad71d..2967d8f 100644
--- a/app/models/service_sorter.rb
+++ b/app/models/service_sorter.rb
@@ -71,10 +71,13 @@ def set_link_port_and_protocol(service, dependency)
         # Finds the explicitly exposed ports (:ports and :expose) on the dependency and
         # creates a hash of the port and protocol for each
         def ports_and_protocols_for(service)
-          return [] unless service.has_key?(:ports)
+          ports = []
 
-          ports = service[:ports].map do |exposed_port|
-            { port: exposed_port[:hostPort], protocol: (exposed_port[:protocol] || 'tcp') }
+          if service[:ports]
+            mapped_ports = service[:ports].map do |exposed_port|
+              { port: exposed_port[:hostPort], protocol: (exposed_port[:protocol] || 'tcp') }
+            end
+            ports.push(mapped_ports).flatten!
           end
 
           if service[:expose]
diff --git a/spec/models/service_sorter_spec.rb b/spec/models/service_sorter_spec.rb
index 0131574..23fcc0f 100644
--- a/spec/models/service_sorter_spec.rb
+++ b/spec/models/service_sorter_spec.rb
@@ -33,6 +33,7 @@
       it 'uses the lowest numbered exposed port as the link port' do
         expect(subject.last[:links].first[:port]).to eq 80
       end
+
       it "uses 'tcp' as the link protocol" do
         expect(subject.last[:links].first[:protocol]).to eq 'tcp'
       end
@@ -92,4 +93,28 @@
       expect(described_class.send(:get_service_names_for, links)).to contain_exactly("FOO", "BAZ")
     end
   end
+
+  describe '.ports_and_protocols_for' do
+    it 'responds with mapped ports when there are only mapped ports' do
+      service = { ports: [{ hostPort: 80, protocol: 'tcp' }] }
+      expect(described_class.send(:ports_and_protocols_for, service)).to match_array([{ port: 80, protocol: 'tcp' }])
+    end
+
+
+    it 'responds with exposed ports when there are only exposed ports' do
+      service = { expose: [80] }
+      expect(described_class.send(:ports_and_protocols_for, service)).to match_array([{ port: 80, protocol: 'tcp' }])
+    end
+
+    it 'combines mapped and exposed ports if there are both' do
+      service = { expose: [80], ports: [{ hostPort: 8080, protocol: 'tcp' }] }
+      expect(described_class.send(:ports_and_protocols_for, service)).to match_array([{ port: 80, protocol: 'tcp' },
+                                                                                      { port: 8080, protocol: 'tcp' }])
+    end
+
+    it 'returns an empty array if there no mapped or exposed ports' do
+      service = { expose: [], ports: [] }
+      expect(described_class.send(:ports_and_protocols_for, service)).to match_array([])
+    end
+  end
 end