diff --git a/mercurial/narrowspec.py b/mercurial/narrowspec.py
--- a/mercurial/narrowspec.py
+++ b/mercurial/narrowspec.py
@@ -346,6 +346,9 @@
         ds.drop(f)
 
     pctx = repo[b'.']
+
+    # only update added files that are in the sparse checkout
+    addedmatch = matchmod.intersectmatchers(addedmatch, sparse.matcher(repo))
     newfiles = [f for f in pctx.manifest().walk(addedmatch) if f not in ds]
     for f in newfiles:
         ds.normallookup(f)
diff --git a/tests/test-narrow-sparse.t b/tests/test-narrow-sparse.t
--- a/tests/test-narrow-sparse.t
+++ b/tests/test-narrow-sparse.t
@@ -70,3 +70,37 @@
   treemanifest (tree !)
 
   $ hg debugrebuilddirstate
+
+We only make the following assertions for the flat test case since in the
+treemanifest test case debugsparse fails with "path ends in directory
+separator: outside/" which seems like a bug unrelated to the regression this is
+testing for.
+
+#if flat
+widening with both sparse and narrow is possible
+
+  $ cat >> .hg/hgrc <<EOF
+  > [extensions]
+  > sparse = 
+  > narrow = 
+  > EOF
+
+  $ hg debugsparse -X outside/f -X widest/f
+  $ hg tracked -q --addinclude outside/f
+  $ tree
+  .
+  `-- inside
+      `-- f
+  
+  1 directory, 1 file
+
+  $ hg debugsparse -d outside/f
+  $ tree
+  .
+  |-- inside
+  |   `-- f
+  `-- outside
+      `-- f
+  
+  2 directories, 2 files
+#endif