diff --git a/hgext/phabricator.py b/hgext/phabricator.py
--- a/hgext/phabricator.py
+++ b/hgext/phabricator.py
@@ -830,9 +830,11 @@
     repo = ctx.repo()
     repophid = getrepophid(repo)
     # Create a "Differential Diff" via "differential.creatediff" API
+    bookmark = ctx.bookmarks()[0] if ctx.bookmarks() else None
     pdiff = phabdiff(
         sourceControlBaseRevision=b'%s' % ctx.p1().hex(),
         branch=b'%s' % ctx.branch(),
+        bookmark=bookmark,
     )
     modified, added, removed, _d, _u, _i, _c = ctx.p1().status(ctx)
     # addadded will remove moved files from removed, so addremoved won't get