diff --git a/README.md b/README.md
index a0d4d00..9dab3ca 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,11 @@ framework concepts.
 [dependencies]
 heuropt = "0.1"
 
-# Optional: derive serde::{Serialize, Deserialize} on the core data types.
-# heuropt = { version = "0.1", features = ["serde"] }
+# Optional features:
+# - "serde":     derive Serialize/Deserialize on the core data types.
+# - "parallel":  evaluate populations across rayon's thread pool.
+#                Seeded runs stay bit-identical to serial mode.
+# heuropt = { version = "0.1", features = ["serde", "parallel"] }
 ```
 
 ## Define a problem