diff --git a/lib/pact_broker/pacts/service.rb b/lib/pact_broker/pacts/service.rb
index 955677310..70b059772 100644
--- a/lib/pact_broker/pacts/service.rb
+++ b/lib/pact_broker/pacts/service.rb
@@ -59,7 +59,7 @@ def merge_pact params
         consumer_version = version_repository.find_by_pacticipant_id_and_number_or_create consumer.id, params[:consumer_version_number]
         existing_pact = pact_repository.find_by_version_and_provider(consumer_version.id, provider.id)
 
-        params.merge!(json_content: Merger.merge_pacts(params[:json_content], existing_pact.json_content))
+        params.merge!(json_content: Merger.merge_pacts(existing_pact.json_content, params[:json_content]))
 
         update_pact params, existing_pact
       end
diff --git a/spec/features/merge_pact_spec.rb b/spec/features/merge_pact_spec.rb
index e58ffe416..8b3f8264f 100644
--- a/spec/features/merge_pact_spec.rb
+++ b/spec/features/merge_pact_spec.rb
@@ -29,7 +29,7 @@
     let(:merged_pact_content) { load_fixture('a_consumer-a_provider-merged.json') }
 
     before do
-      TestDataBuilder.new.create_pact_with_hierarchy("A Consumer", "1.2.3", "A Provider", existing_pact_content).and_return(:pact)
+      TestDataBuilder.new.create_pact_with_hierarchy("A Consumer", "1.2.3", "A Provider", existing_pact_content)
     end
 
     it "returns a 200 Success" do
diff --git a/spec/fixtures/a_consumer-a_provider-merged.json b/spec/fixtures/a_consumer-a_provider-merged.json
index bdebe24d2..73fbe7f3a 100644
--- a/spec/fixtures/a_consumer-a_provider-merged.json
+++ b/spec/fixtures/a_consumer-a_provider-merged.json
@@ -7,11 +7,11 @@
   },
   "interactions": [
     {
-      "description" : "a request for something",
+      "description" : "another request for something",
       "providerState": null,
       "request": {
         "method": "get",
-        "path" : "/something"
+        "path" : "/something_else"
       },
       "response": {
         "status": 200,
@@ -19,11 +19,11 @@
       }
     },
     {
-      "description" : "another request for something",
+      "description" : "a request for something",
       "providerState": null,
       "request": {
         "method": "get",
-        "path" : "/something_else"
+        "path" : "/something"
       },
       "response": {
         "status": 200,