diff --git a/README.md b/README.md
index 502df89..846eb61 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,8 @@ Enables `serde` derives.
 
 Uses [`bytes`](https://github.com/tokio-rs/bytes) as the underlying `Slice` type.
 
+*Disabled by default.*
+
 ## Stable disk format
 
 The disk format is stable as of 1.0.0. Future breaking changes will result in a major version bump and a migration path.