diff --git a/src/security/detail/openssl-helper.hpp b/src/security/detail/openssl-helper.hpp
index ddd1ea6..dfc630d 100644
--- a/src/security/detail/openssl-helper.hpp
+++ b/src/security/detail/openssl-helper.hpp
@@ -32,6 +32,9 @@
 const EVP_MD*
 toDigestEvpMd(DigestAlgorithm algo);
 
+int
+getEvpPkeyType(EVP_PKEY* key);
+
 class EvpPkeyCtx : noncopyable
 {
 public: