diff --git a/contrib/buildbot/phabricator_wrapper.py b/contrib/buildbot/phabricator_wrapper.py
--- a/contrib/buildbot/phabricator_wrapper.py
+++ b/contrib/buildbot/phabricator_wrapper.py
@@ -368,7 +368,7 @@
 
     def get_revision_changed_files(self, revision_id):
         return list(self.differential.getcommitpaths(
-            revision_id=revision_id).values())
+            revision_id=int(revision_id)).values())
 
     def get_file_content_from_master(self, path):
         latest_commit_hash = self.get_latest_master_commit_hash()
diff --git a/contrib/buildbot/test/test_endpoint_buildDiff.py b/contrib/buildbot/test/test_endpoint_buildDiff.py
--- a/contrib/buildbot/test/test_endpoint_buildDiff.py
+++ b/contrib/buildbot/test/test_endpoint_buildDiff.py
@@ -21,7 +21,7 @@
     def __init__(self):
         self.stagingRef = "refs/tags/phabricator/diff/1234"
         self.targetPHID = "PHID-HMBT-123456"
-        self.revisionId = "D1234"
+        self.revisionId = "1234"
 
     def __str__(self):
         return "?{}".format("&".join("{}={}".format(key, value)