diff --git a/vfs/atomicfs/marker.go b/vfs/atomicfs/marker.go
index 99bf60243c..22bbd554a0 100644
--- a/vfs/atomicfs/marker.go
+++ b/vfs/atomicfs/marker.go
@@ -2,7 +2,7 @@
 // of this source code is governed by a BSD-style license that can be found in
 // the LICENSE file.
 
-package vfs
+package atomicfs
 
 import (
 	"fmt"
@@ -195,6 +195,13 @@ func (a *Marker) Move(filename string) error {
 	return nil
 }
 
+// NextIter returns the next iteration number that the marker will use.
+// Clients may use this number for formulating filenames that are
+// unused.
+func (a *Marker) NextIter() uint64 {
+	return a.iter + 1
+}
+
 // RemoveObsolete removes any obsolete files discovered while locating
 // the marker or files unable to be removed during Move.
 func (a *Marker) RemoveObsolete() error {
diff --git a/vfs/atomicfs/marker_test.go b/vfs/atomicfs/marker_test.go
index 37d03f02bb..5668d25394 100644
--- a/vfs/atomicfs/marker_test.go
+++ b/vfs/atomicfs/marker_test.go
@@ -2,7 +2,7 @@
 // of this source code is governed by a BSD-style license that can be found in
 // the LICENSE file.
 
-package vfs
+package atomicfs
 
 import (
 	"bytes"
@@ -117,6 +117,14 @@ func TestMarker(t *testing.T) {
 			}
 			return ""
 
+		case "next-iter":
+			var dir, marker string
+			td.ScanArgs(t, "dir", &dir)
+			td.ScanArgs(t, "marker", &marker)
+			m := markers[memFS.PathJoin(dir, marker)]
+			require.NotNil(t, m)
+			return fmt.Sprintf("%d", m.NextIter())
+
 		case "remove-obsolete":
 			var dir, marker string
 			td.ScanArgs(t, "dir", &dir)
diff --git a/vfs/atomicfs/testdata/marker b/vfs/atomicfs/testdata/marker
index ffb7a7a71a..2450bd24bf 100644
--- a/vfs/atomicfs/testdata/marker
+++ b/vfs/atomicfs/testdata/marker
@@ -10,6 +10,14 @@ mkdir-all data
 locate dir=data marker=foo
 ----
 
+next-iter  dir=data marker=foo
+----
+1
+
+next-iter  dir=data marker=foo
+----
+1
+
 # The directory should still be empty.
 list data
 ----
@@ -23,11 +31,19 @@ list data
 ----
 marker.foo.000001.MANIFEST-000010
 
+next-iter  dir=data marker=foo
+----
+2
+
 # Moving the marker should move the existing marker file.
 move dir=data marker=foo
 MANIFEST-000016
 ----
 
+next-iter  dir=data marker=foo
+----
+3
+
 list data
 ----
 marker.foo.000002.MANIFEST-000016