diff --git a/contrib/import-checker.py b/contrib/import-checker.py
--- a/contrib/import-checker.py
+++ b/contrib/import-checker.py
@@ -24,6 +24,7 @@
 allowsymbolimports = (
     '__future__',
     'breezy',
+    'concurrent',
     'hgclient',
     'mercurial',
     'mercurial.hgweb.common',