diff --git a/mountpoint-s3/tests/reftests/harness.rs b/mountpoint-s3/tests/reftests/harness.rs
index 5202a91b0..b5130e75f 100644
--- a/mountpoint-s3/tests/reftests/harness.rs
+++ b/mountpoint-s3/tests/reftests/harness.rs
@@ -1290,4 +1290,24 @@ mod mutations {
             0,
         )
     }
+
+    #[test]
+    fn regression_put_nested_over_open_file() {
+        run_test(
+            TreeNode::Directory(BTreeMap::from([])),
+            vec![
+                Op::CreateFile(
+                    ValidName("a".into()),
+                    DirectoryIndex(0),
+                    FileContent(0, FileSize::Small(0)),
+                ),
+                Op::PutObject(
+                    DirectoryIndex(0),
+                    Name("a/-".into()),
+                    FileContent(0, FileSize::Small(0)),
+                ),
+            ],
+            0,
+        )
+    }
 }