diff --git a/lib/pact_broker/pacts/merger.rb b/lib/pact_broker/pacts/merger.rb
index 84a99c74a..8a82b6d1b 100644
--- a/lib/pact_broker/pacts/merger.rb
+++ b/lib/pact_broker/pacts/merger.rb
@@ -9,10 +9,14 @@ module Merger
       def conflict? original_json, additional_json
         original, additional = [original_json, additional_json].map{|str| JSON.parse(str, PACT_PARSING_OPTIONS) }
 
-        additional["interactions"].any? do |new_interaction|
-          original["interactions"].any? do |original_interaction|
-            same_description_and_state?(original_interaction, new_interaction) &&
-              !same_request_properties?(original_interaction["request"], new_interaction["request"])
+        if original["interactions"].nil? || additional["interactions"].nil?
+          true
+        else
+          additional["interactions"].any? do |new_interaction|
+            original["interactions"].any? do |original_interaction|
+              same_description_and_state?(original_interaction, new_interaction) &&
+                !same_request_properties?(original_interaction["request"], new_interaction["request"])
+            end
           end
         end
       end
diff --git a/spec/lib/pact_broker/pacts/merger_spec.rb b/spec/lib/pact_broker/pacts/merger_spec.rb
index ca0a248ab..f87123bb3 100644
--- a/spec/lib/pact_broker/pacts/merger_spec.rb
+++ b/spec/lib/pact_broker/pacts/merger_spec.rb
@@ -160,6 +160,16 @@ def merge_pacts(a, b, return_hash = true)
             pact_to_compare["interactions"][0]["request"]["headers"].delete("Content-Type")
             expect(compare_pacts(example_pact, pact_to_compare)).to eq true
           end
+
+          it "returns true if the existing pact has no interactions and the new one does" do
+            example_pact["interactions"] = nil
+            expect(compare_pacts(example_pact, pact_to_compare)).to eq true
+          end
+
+          it "returns true if the new pact has no interactions and the existing one does" do
+            pact_to_compare["interactions"] = nil
+            expect(compare_pacts(example_pact, pact_to_compare)).to eq true
+          end
         end
 
         def compare_pacts(a, b)