diff --git a/ssl/ssl.h b/ssl/ssl.h
index 256d1c32a..376dd6981 100644
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -2098,7 +2098,7 @@ void SSL_set_cert_cb(SSL *s, int (*cb)(SSL *ssl, void *arg), void *arg);
 #ifndef OPENSSL_NO_RSA
 int	SSL_use_RSAPrivateKey(SSL *ssl, RSA *rsa);
 #endif
-int	SSL_use_RSAPrivateKey_ASN1(SSL *ssl, unsigned char *d, long len);
+int	SSL_use_RSAPrivateKey_ASN1(SSL *ssl, const unsigned char *d, long len);
 int	SSL_use_PrivateKey(SSL *ssl, EVP_PKEY *pkey);
 int	SSL_use_PrivateKey_ASN1(int pk,SSL *ssl, const unsigned char *d, long len);
 int	SSL_use_certificate(SSL *ssl, X509 *x);
diff --git a/ssl/ssl_rsa.c b/ssl/ssl_rsa.c
index 7c02878ab..c76a2a37c 100644
--- a/ssl/ssl_rsa.c
+++ b/ssl/ssl_rsa.c
@@ -296,7 +296,7 @@ end:
 	}
 #endif
 
-int SSL_use_RSAPrivateKey_ASN1(SSL *ssl, unsigned char *d, long len)
+int SSL_use_RSAPrivateKey_ASN1(SSL *ssl, const unsigned char *d, long len)
 	{
 	int ret;
 	const unsigned char *p;