diff --git a/CHANGELOG.md b/CHANGELOG.md
index a1b20faa3..fc130bbf0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ## Master
 
+* Calling CircleCI API when `CI_PULL_REQUEST` is not set - marcelofabri
 * Look inside PR JSON for the commit range (instead of getting from CI providers) - marcelofabri
 * Adds `pr_labels` to DSL - marcelofabri
 * Makes the CircleCI provider validate, but not run on non-PR builds - orta
diff --git a/lib/danger/ci_source/circle.rb b/lib/danger/ci_source/circle.rb
index 1dbc2ad22..f4b070226 100644
--- a/lib/danger/ci_source/circle.rb
+++ b/lib/danger/ci_source/circle.rb
@@ -1,16 +1,43 @@
 # https://circleci.com/docs/environment-variables
 require 'uri'
+require 'danger/circle_api'
 
 module Danger
   module CISource
     class CircleCI < CI
       def self.validates?(env)
-        return !env["CIRCLE_BUILD_NUM"].nil? && !env["CI_PULL_REQUEST"].nil?
+        return false if env["CIRCLE_BUILD_NUM"].nil?
+        return true unless env["CI_PULL_REQUEST"].nil?
+
+        return !env["CIRCLE_PROJECT_USERNAME"].nil? && !env["CIRCLE_PROJECT_REPONAME"].nil?
+      end
+
+      def client
+        @client ||= CircleAPI.new(@circle_token)
+      end
+
+      def fetch_pull_request_url(repo_slug, build_number)
+        build_json = client.fetch_build(repo_slug, build_number)
+        build_json[:pull_request_urls].first
+      end
+
+      def pull_request_url(env)
+        url = env["CI_PULL_REQUEST"]
+
+        if url.nil? && !env["CIRCLE_PROJECT_USERNAME"].nil? && !env["CIRCLE_PROJECT_REPONAME"].nil?
+          repo_slug = env["CIRCLE_PROJECT_USERNAME"] + "/" + env["CIRCLE_PROJECT_REPONAME"]
+          url = fetch_pull_request_url(repo_slug, env["CIRCLE_BUILD_NUM"])
+        end
+
+        url
       end
 
       def initialize(env)
-        if URI.parse(env["CI_PULL_REQUEST"]).path.split("/").count == 5
-          paths = URI.parse(env["CI_PULL_REQUEST"]).path.split("/")
+        @circle_token = env["CIRCLE_CI_API_TOKEN"]
+        url = pull_request_url(env)
+
+        if URI.parse(url).path.split("/").count == 5
+          paths = URI.parse(url).path.split("/")
           # The first one is an extra slash, ignore it
           self.repo_slug = paths[1] + "/" + paths[2]
           self.pull_request_id = paths[4]
diff --git a/lib/danger/circle_api.rb b/lib/danger/circle_api.rb
new file mode 100644
index 000000000..4167c318a
--- /dev/null
+++ b/lib/danger/circle_api.rb
@@ -0,0 +1,23 @@
+require 'faraday'
+
+module Danger
+  class CircleAPI
+    attr_accessor :circle_token
+
+    def initialize(circle_token = nil)
+      self.circle_token = circle_token
+    end
+
+    def client
+      @client ||= Faraday.new(url: 'https://circleci.com/api/v1')
+    end
+
+    def fetch_build(repo_slug, build_number)
+      url = "project/#{repo_slug}/#{build_number}"
+      params = { :'circle-token' => circle_token }
+      response = client.get url, params, accept: 'application/json'
+      json = JSON.parse(response.body, symbolize_names: true)
+      json
+    end
+  end
+end
diff --git a/spec/fixtures/circle_build_response.json b/spec/fixtures/circle_build_response.json
new file mode 100644
index 000000000..21805fc38
--- /dev/null
+++ b/spec/fixtures/circle_build_response.json
@@ -0,0 +1 @@
+{"compare":"https://github.com/artsy/eigen/commit/1b064fe71ac7","previous_successful_build":{"build_num":1498,"status":"success","build_time_millis":544632},"build_parameters":null,"oss":true,"committer_date":"2016-02-10T09:30:48Z","steps":[{"name":"Starting the build","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"Starting the build","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:18.526Z","type":"infrastructure","output_url":"https://circle-production-action-output.s3.amazonaws.com/d52d558a91055bdd2630bb65-artsy-eigen-0-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=GvKkVCxkz09%2FT88TAmRkU9N09VU%3D","start_time":"2016-02-10T09:31:14.802Z","exit_code":null,"canceled":null,"step":0,"run_time_millis":3724,"has_output":true}]},{"name":"Start container","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"Start container","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:20.274Z","source":"config","type":"infrastructure","output_url":"https://circle-production-action-output.s3.amazonaws.com/e52d558a91055bdd6630bb65-artsy-eigen-1-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=MZQlsp6X9Xu6iBZl5CLkEkcakXk%3D","start_time":"2016-02-10T09:31:18.532Z","exit_code":0,"canceled":null,"step":1,"run_time_millis":1742,"has_output":true}]},{"name":"Enable SSH","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"Enable SSH","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:20.921Z","type":"infrastructure","output_url":"https://circle-production-action-output.s3.amazonaws.com/f52d558a91055bdd8630bb65-artsy-eigen-2-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=L%2Bb8L6prU6aiBeXmOMspWEQCB58%3D","start_time":"2016-02-10T09:31:20.280Z","exit_code":null,"canceled":null,"step":2,"run_time_millis":641,"has_output":true}]},{"name":"Restore source cache","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"Restore source cache","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:24.518Z","source":"cache","type":"checkout","output_url":"https://circle-production-action-output.s3.amazonaws.com/062d558a91055bdd8630bb65-artsy-eigen-3-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=aRa%2Fs2%2BI4btp9dAIt7DEuliKjFc%3D","start_time":"2016-02-10T09:31:20.929Z","exit_code":null,"canceled":null,"step":3,"run_time_millis":3589,"has_output":true}]},{"name":"Checkout using deploy key: c1:49:95:9d:84:4e:36:1a:78:d7:bc:bd:e6:6a:4e:2a","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"Checkout using deploy key: c1:49:95:9d:84:4e:36:1a:78:d7:bc:bd:e6:6a:4e:2a","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:27.443Z","source":"config","type":"checkout","output_url":"https://circle-production-action-output.s3.amazonaws.com/162d558a91055bddc630bb65-artsy-eigen-4-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=306MVpVbp%2F81mJlm4E56WlWsjks%3D","start_time":"2016-02-10T09:31:24.525Z","exit_code":0,"canceled":null,"step":4,"run_time_millis":2918,"has_output":true}]},{"name":"Configure the build","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"Configure the build","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:29.117Z","source":"cache","type":"machine","output_url":"https://circle-production-action-output.s3.amazonaws.com/262d558a91055bddf630bb65-artsy-eigen-5-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=Tucr%2BPveBtJ%2BbYpqeXm2ZkBzYII%3D","start_time":"2016-02-10T09:31:27.451Z","exit_code":null,"canceled":null,"step":5,"run_time_millis":1666,"has_output":true}]},{"name":"Exporting env vars from circle.yml","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"Exporting env vars from circle.yml","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:29.427Z","source":"config","type":"machine","output_url":"https://circle-production-action-output.s3.amazonaws.com/362d558a91055bdd1730bb65-artsy-eigen-6-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=yUtEfy0xtAUoqCZqxb6ztZB46hw%3D","start_time":"2016-02-10T09:31:29.123Z","exit_code":0,"canceled":null,"step":6,"run_time_millis":304,"has_output":true}]},{"name":"Exporting env vars from project settings","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"Exporting env vars from project settings","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:29.737Z","source":"db","type":"machine","output_url":"https://circle-production-action-output.s3.amazonaws.com/462d558a91055bdd1730bb65-artsy-eigen-7-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=rb60MLo682KnK%2Fg59UhdomgsxA0%3D","start_time":"2016-02-10T09:31:29.433Z","exit_code":0,"canceled":null,"step":7,"run_time_millis":304,"has_output":true}]},{"name":"Select Xcode Version","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"Select Xcode Version","bash_command":"sudo xcode-select --switch /Applications/Xcode-7.2.app","status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:30.056Z","source":"inference","type":"machine","start_time":"2016-02-10T09:31:29.744Z","exit_code":0,"canceled":null,"step":8,"run_time_millis":312,"has_output":false}]},{"name":"Restore cache","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"Restore cache","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:35.580Z","source":"cache","type":"machine","output_url":"https://circle-production-action-output.s3.amazonaws.com/662d558a91055bdd2730bb65-artsy-eigen-9-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=LBFcAZJjt0x1HxXY6yRJ7%2FC4XuY%3D","start_time":"2016-02-10T09:31:30.061Z","exit_code":null,"canceled":null,"step":9,"run_time_millis":5519,"has_output":true}]},{"name":"echo \"machine github.com login $GITHUB_API_KEY\" > ~/.netrc","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"echo \"machine github.com login $GITHUB_API_KEY\" > ~/.netrc","bash_command":"echo \"machine github.com login $GITHUB_API_KEY\" > ~/.netrc","status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:35.901Z","source":"config","type":"machine","start_time":"2016-02-10T09:31:35.588Z","exit_code":0,"canceled":null,"step":10,"run_time_millis":313,"has_output":false}]},{"name":"chmod 600 ~/.netrc","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"chmod 600 ~/.netrc","bash_command":"chmod 600 ~/.netrc","status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:36.209Z","source":"config","type":"machine","start_time":"2016-02-10T09:31:35.906Z","exit_code":0,"canceled":null,"step":11,"run_time_millis":303,"has_output":false}]},{"name":"bundle check --path=vendor/bundle || bundle install --path=vendor/bundle --jobs=4 --retry=3 --without development","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"bundle check --path=vendor/bundle || bundle install --path=vendor/bundle --jobs=4 --retry=3 --without development","bash_command":"bundle check --path=vendor/bundle || bundle install --path=vendor/bundle --jobs=4 --retry=3 --without development","status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:31:48.838Z","source":"config","type":"dependencies","output_url":"https://circle-production-action-output.s3.amazonaws.com/962d558a91055bdd8730bb65-artsy-eigen-12-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=%2F%2Bf7p7FJGLTmOKOtyoxYg%2FC2k6U%3D","start_time":"2016-02-10T09:31:36.216Z","exit_code":0,"canceled":null,"step":12,"run_time_millis":12622,"has_output":true}]},{"name":"bundle exec pod install","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"bundle exec pod install","bash_command":"bundle exec pod install","status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:32:57.758Z","source":"config","type":"dependencies","output_url":"https://circle-production-action-output.s3.amazonaws.com/b62d558a91055bdd4830bb65-artsy-eigen-13-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=a9xEa59TgN2%2Bu8CsB4JiakLxNMY%3D","start_time":"2016-02-10T09:31:48.843Z","exit_code":0,"canceled":null,"step":13,"run_time_millis":68915,"has_output":true}]},{"name":"Save cache","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"Save cache","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:33:07.495Z","source":"cache","type":"database","output_url":"https://circle-production-action-output.s3.amazonaws.com/c72d558a91055bdd9c30bb65-artsy-eigen-14-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=tsAhNUOYU0fIU4QjUtEhlbxHbXk%3D","start_time":"2016-02-10T09:32:57.765Z","exit_code":null,"canceled":null,"step":14,"run_time_millis":9730,"has_output":true}]},{"name":"make ci","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"make ci","bash_command":"make 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--base=master","status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:37:34.374Z","source":"config","type":"test","output_url":"https://circle-production-action-output.s3.amazonaws.com/cc2d558a91055bdddd40bb65-artsy-eigen-17-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=WmzEzDMc4Ip2mqjAzEZvzbisewg%3D","start_time":"2016-02-10T09:37:33.059Z","exit_code":0,"canceled":null,"step":17,"run_time_millis":1315,"has_output":true}]},{"name":"make deploy_if_beta_branch","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"make deploy_if_beta_branch","bash_command":"make 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metadata","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:37:36.011Z","type":"teardown","output_url":"https://circle-production-action-output.s3.amazonaws.com/fc2d558a91055bdded40bb65-artsy-eigen-19-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=5k7FDPElcqsjdJt707U%2Bz2JC5%2F8%3D","start_time":"2016-02-10T09:37:34.692Z","exit_code":null,"canceled":null,"step":19,"run_time_millis":1319,"has_output":true}]},{"name":"Collect artifacts","actions":[{"truncated":false,"index":0,"parallel":true,"failed":null,"infrastructure_fail":null,"name":"Collect artifacts","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:37:48.618Z","type":"teardown","output_url":"https://circle-production-action-output.s3.amazonaws.com/0d2d558a91055bdd0e40bb65-artsy-eigen-20-0?AWSAccessKeyId=AKIAIQ65EYQDTMSJK2DQ&Expires=1613026953&Signature=08TVUfEX0hEmhroEerTD5l8JAWs%3D","start_time":"2016-02-10T09:37:36.020Z","exit_code":null,"canceled":null,"step":20,"run_time_millis":12598,"has_output":true}]},{"name":"Ensure caches are uploaded","actions":[{"truncated":false,"index":0,"parallel":false,"failed":null,"infrastructure_fail":null,"name":"Ensure caches are 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SSH","bash_command":null,"status":"success","timedout":null,"continue":null,"end_time":"2016-02-10T09:37:48.655Z","type":"teardown","start_time":"2016-02-10T09:37:48.647Z","exit_code":null,"canceled":null,"step":23,"run_time_millis":8,"has_output":false}]}],"body":"","usage_queued_at":"2016-02-10T09:30:59.176Z","retry_of":null,"reponame":"eigen","ssh_users":[],"build_url":"https://circleci.com/gh/artsy/eigen/1500","parallel":1,"failed":true,"branch":"orta-dm_pilot","username":"artsy","author_date":"2016-02-10T09:30:48Z","why":"github","user":{"is_user":true,"login":"orta","name":"Orta","email":"orta@artsymail.com","avatar_url":"https://avatars.githubusercontent.com/u/49038?v=3"},"vcs_revision":"1b064fe71ac7ec073223221889d96dcecb292000","owners":["orta"],"vcs_tag":null,"build_num":1500,"infrastructure_fail":false,"ssh_enabled":false,"committer_email":"orta.therox@gmail.com","has_artifacts":true,"previous":null,"status":"failed","committer_name":"Orta Therox","pull_request_urls":["https://github.com/artsy/eigen/pull/1130"],"retries":[1501],"subject":"Use the latest Danger / pilot","vcs_type":"github","timedout":false,"dont_build":null,"lifecycle":"finished","no_dependency_cache":null,"stop_time":"2016-02-10T09:37:49.133Z","build_time_millis":398863,"circle_yml":{"string":"machine:\n  xcode:\n    version: \"7.2\"\n  environment:\n    # Public - Yay\n    UPLOAD_IOS_SNAPSHOT_BUCKET_NAME: eigen-ci\n\n    # Private - Keeps us in business! Yay\n    AWS_ACCESS_KEY_ID: from_admin\n    AWS_SECRET_ACCESS_KEY: from_admin\n    DANGER_GITHUB_API_TOKEN: from_admin\n    GITHUB_API_KEY : from_admin\n    MATCH_PASSWORD : from_admin\n    HOCKEY_API_TOKEN : from_admin\n    FASTLANE_USERNAME : from_admin\n    FASTLANE_PASSWORD : from_admin\n    ArtsyAPIClientSecret: from_admin\n    ArtsyAPIClientKey: from_admin\n    ArtsyFacebookAppID: from_admin\n    ArtsyTwitterKey: from_admin\n    ArtsyTwitterSecret: from_admin\n    ArtsyTwitterStagingKey: from_admin\n    ArtsyTwitterStagingSecret: from_admin\n    SegmentProductionWriteKey: from_admin\n    SegmentDevWriteKey: from_admin\n    AdjustProductionAppToken: from_admin\n    ArtsyEchoProductionToken:  from_admin\n\n  post:\n    - echo \"machine github.com login $GITHUB_API_KEY\" > ~/.netrc\n    - chmod 600 ~/.netrc\n\ndependencies:\n  override:\n    - bundle check --path=vendor/bundle || bundle install --path=vendor/bundle --jobs=4 --retry=3 --without development\n    - bundle exec pod install\n  cache_directories:\n    - vendor/bundle\n    - Pods\n\ntest:\n  pre:\n    - make ci\n  override:\n    - make test\n    - bundle exec danger --verbose --base=master\n  post:\n    - make deploy_if_beta_branch\n"},"messages":[],"is_first_green_build":false,"job_name":null,"start_time":"2016-02-10T09:31:10.270Z","canceler":null,"all_commit_details":[{"committer_date":"2016-02-10T09:30:48Z","body":"","branch":"orta-dm_pilot","author_date":"2016-02-10T09:30:48Z","committer_email":"orta.therox@gmail.com","commit":"1b064fe71ac7ec073223221889d96dcecb292000","committer_login":"orta","committer_name":"Orta Therox","subject":"Use the latest Danger / pilot","commit_url":"https://github.com/artsy/eigen/commit/1b064fe71ac7ec073223221889d96dcecb292000","author_login":"orta","author_name":"Orta Therox","author_email":"orta.therox@gmail.com"}],"outcome":"failed","vcs_url":"https://github.com/artsy/eigen","author_name":"Orta Therox","node":[{"public_ip_addr":"162.217.87.35","port":55003,"username":"distiller","image_id":null,"ssh_enabled":null}],"queued_at":"2016-02-10T09:31:10.160Z","canceled":false,"author_email":"orta.therox@gmail.com"}
\ No newline at end of file
diff --git a/spec/sources/circle_api_spec.rb b/spec/sources/circle_api_spec.rb
new file mode 100644
index 000000000..ada27d69f
--- /dev/null
+++ b/spec/sources/circle_api_spec.rb
@@ -0,0 +1,42 @@
+require 'spec_helper'
+require 'danger/circle_api'
+
+describe Danger::CircleAPI do
+  api_path = "project/artsy/eigen/1500"
+  accept_json = { accept: 'application/json' }
+
+  before do
+    build_response = fixture("circle_build_response")
+    @mocked_response = Faraday::Response.new(body: build_response, status: 200)
+    @expected_json_response = JSON.parse(build_response, symbolize_names: true)
+  end
+
+  it 'has a nil token as default' do
+    api = Danger::CircleAPI.new
+    expect(api.circle_token).to be nil
+  end
+
+  it 'sets the token on initialize' do
+    api = Danger::CircleAPI.new('123456')
+    expect(api.circle_token).to eql('123456')
+  end
+
+  it 'creates a client with the correct base url' do
+    api = Danger::CircleAPI.new
+    expect(api.client.url_prefix.to_s).to eql('https://circleci.com/api/v1')
+  end
+
+  it 'fetches the build info without token' do
+    api = Danger::CircleAPI.new
+    allow(api.client).to receive(:get).with(api_path, { :'circle-token' => nil }, accept_json).and_return(@mocked_response)
+
+    expect(api.fetch_build("artsy/eigen", "1500")).to eql(@expected_json_response)
+  end
+
+  it 'fetches the build info with token' do
+    api = Danger::CircleAPI.new('123456')
+    allow(api.client).to receive(:get).with(api_path, { :'circle-token' => '123456' }, accept_json).and_return(@mocked_response)
+
+    expect(api.fetch_build("artsy/eigen", "1500")).to eql(@expected_json_response)
+  end
+end
diff --git a/spec/sources/circle_spec.rb b/spec/sources/circle_spec.rb
index 9a3b430d8..ae1afaf47 100644
--- a/spec/sources/circle_spec.rb
+++ b/spec/sources/circle_spec.rb
@@ -15,6 +15,14 @@
     expect(Danger::CISource::CircleCI.validates?(env)).to be true
   end
 
+  it 'validates when circle env var is found and it has no PR url' do
+    env = { "CIRCLE_BUILD_NUM" => "true",
+      "CIRCLE_PROJECT_USERNAME" => "orta",
+      "CIRCLE_PROJECT_REPONAME" => "thing"
+    }
+    expect(Danger::CISource::CircleCI.validates?(env)).to be true
+  end
+
   it 'doesnt get a PR id when it has a bad PR url' do
     env = { "CIRCLE_BUILD_NUM" => "true", "CI_PULL_REQUEST" => not_legit_pr }
     t = Danger::CISource::CircleCI.new(env)
@@ -36,4 +44,34 @@
     expect(t.repo_slug).to eql("artsy/eigen")
     expect(t.pull_request_id).to eql("800")
   end
+
+  it 'gets out a repo slug, pull request number and commit refs when PR url is not found' do
+    env = {
+      "CIRCLE_BUILD_NUM" => "1500",
+      "CIRCLE_PROJECT_USERNAME" => "artsy",
+      "CIRCLE_PROJECT_REPONAME" => "eigen",
+      "CIRCLE_COMPARE_URL" => "https://github.com/artsy/eigen/compare/759adcbd0d8f...13c4dc8bb61d"
+    }
+    build_response = JSON.parse(fixture("circle_build_response"), symbolize_names: true)
+    allow_any_instance_of(Danger::CircleAPI).to receive(:fetch_build).with("artsy/eigen", "1500").and_return(build_response)
+
+    t = Danger::CISource::CircleCI.new(env)
+
+    expect(t.repo_slug).to eql("artsy/eigen")
+    expect(t.pull_request_id).to eql("1130")
+  end
+
+  it 'uses Circle CI API token if available' do
+    env = {
+      "CIRCLE_BUILD_NUM" => "1500",
+      "CIRCLE_CI_API_TOKEN" => "token",
+      "CIRCLE_PROJECT_USERNAME" => "artsy",
+      "CIRCLE_PROJECT_REPONAME" => "eigen"
+    }
+    build_response = JSON.parse(fixture("circle_build_response"), symbolize_names: true)
+    allow_any_instance_of(Danger::CircleAPI).to receive(:fetch_build).with("artsy/eigen", "1500").and_return(build_response)
+
+    t = Danger::CISource::CircleCI.new(env)
+    expect(t.client.circle_token).to eql("token")
+  end
 end