diff --git a/mercurial/hg.py b/mercurial/hg.py
--- a/mercurial/hg.py
+++ b/mercurial/hg.py
@@ -897,7 +897,7 @@ class localrepository:
                 self.ui.warn("%s still exists!\n" % f)
             elif self.dirstate.state(f) == 'a':
                 self.ui.warn("%s never committed!\n" % f)
-                self.dirstate.forget(f)
+                self.dirstate.forget([f])
             elif f not in self.dirstate:
                 self.ui.warn("%s not tracked!\n" % f)
             else: