diff --git a/src/lib.rs b/src/lib.rs
index c5ca4a8..a10ac2f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -112,7 +112,6 @@
 
 #[macro_use]
 extern crate arrayref;
-extern crate sha2;
 extern crate curve25519_dalek;
 extern crate generic_array;
 extern crate digest;
@@ -124,6 +123,9 @@ extern crate rand;
 #[macro_use]
 extern crate std;
 
+#[cfg(test)]
+extern crate sha2;
+
 #[cfg(test)]
 extern crate rustc_serialize;