diff --git a/src/lib.rs b/src/lib.rs
index 6471dd0..197850e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -69,7 +69,7 @@ use pki_types::PrivateKeyDer;
#[cfg(feature = "std")]
use pki_types::{
CertificateDer, CertificateRevocationListDer, CertificateSigningRequestDer, PrivatePkcs1KeyDer,
- PrivatePkcs8KeyDer, PrivateSec1KeyDer,
+ PrivatePkcs8KeyDer, PrivateSec1KeyDer, SubjectPublicKeyInfoDer,
};
#[cfg(feature = "std")]
@@ -104,7 +104,10 @@ pub fn private_key(rd: &mut dyn io::BufRead) -> Result