diff --git a/mercurial/commit.py b/mercurial/commit.py
--- a/mercurial/commit.py
+++ b/mercurial/commit.py
@@ -389,6 +389,7 @@
     text = fctx.data()
     if (
         fparent2 != repo.nullid
+        or fparent1 == repo.nullid
         or meta
         or flog.cmp(fparent1, text)
         or force_new_node
diff --git a/tests/test-narrow-commit.t b/tests/test-narrow-commit.t
--- a/tests/test-narrow-commit.t
+++ b/tests/test-narrow-commit.t
@@ -105,14 +105,7 @@
   $ hg debugdirstate --no-dates
   n 644         10 set                 inside/f1
 
-Can't commit empty files
+Can commit empty files
 
   $ touch inside/c; hg add inside/c; hg commit -qm _; hg verify -q
-   warning: revlog 'data/inside/c.i' not in fncache!
-   4: empty or missing inside/c
-   inside/c@4: manifest refers to unknown revision 000000000000
-  1 warnings encountered!
-  hint: run "hg debugrebuildfncache" to recover from corrupt fncache
-  2 integrity errors encountered!
-  (first damaged changeset appears to be 4)
-  [1]
+  $ hg cat -r . inside/c