diff --git a/Cargo.toml b/Cargo.toml
index f6db6c0..4704345 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -46,3 +46,4 @@ default = ["std"]
 std = ["rand", "curve25519-dalek/std"]
 bench = []
 nightly = ["curve25519-dalek/nightly"]
+asm = ["sha2/asm"]