diff --git a/lib/pull_request.rb b/lib/pull_request.rb
index 9333175..aaad718 100644
--- a/lib/pull_request.rb
+++ b/lib/pull_request.rb
@@ -40,7 +40,7 @@ def validate_single_commit
   def validate_files_changed
     commit = GitHubClient.instance.commit("alphagov/#{@api_response.base.repo.name}", @api_response.head.sha)
     files_changed = commit.files.map(&:filename)
-    allowed_files = ["yarn.lock", "Gemfile.lock", "Gemfile", "#{@api_response.base.repo.name}.gemspec"]
+    allowed_files = ["yarn.lock", "package.json", "Gemfile.lock", "Gemfile", "#{@api_response.base.repo.name}.gemspec"]
     (files_changed - allowed_files).empty?
   end
 
diff --git a/spec/lib/pull_request_spec.rb b/spec/lib/pull_request_spec.rb
index 053b60e..bc19518 100644
--- a/spec/lib/pull_request_spec.rb
+++ b/spec/lib/pull_request_spec.rb
@@ -219,6 +219,16 @@ def create_pull_request_instance
       expect(pr.validate_files_changed).to eq(true)
     end
 
+    it "returns true if PR changes package.json" do
+      pkg_json = head_commit_api_response[:files].first.dup
+      pkg_json[:filename] = "package.json"
+      head_commit_api_response[:files] << pkg_json
+      stub_remote_commit(head_commit_api_response)
+
+      pr = PullRequest.new(pull_request_api_response)
+      expect(pr.validate_files_changed).to eq(true)
+    end
+
     it "returns false if PR changes anything else" do
       head_commit_api_response[:files][0][:filename] = "something_else.rb"
       stub_remote_commit(head_commit_api_response)