diff --git a/tests/test-share-safe.t b/tests/test-share-safe.t
--- a/tests/test-share-safe.t
+++ b/tests/test-share-safe.t
@@ -7,6 +7,9 @@
   > use-share-safe = True
   > [storage]
   > revlog.persistent-nodemap.slow-path=allow
+  > # enforce zlib to ensure we can upgrade to zstd later
+  > [format]
+  > revlog-compression=zlib
   > EOF
 
 prepare source repo