diff --git a/src/tpm2-tss-engine-ecc.c b/src/tpm2-tss-engine-ecc.c
index 9e72c85..f6b9c5a 100644
--- a/src/tpm2-tss-engine-ecc.c
+++ b/src/tpm2-tss-engine-ecc.c
@@ -52,7 +52,7 @@ EC_KEY_METHOD *ecc_methods = NULL;
 #endif /* OPENSSL_VERSION_NUMBER < 0x10100000 */
 
 #ifdef HAVE_OPENSSL_DIGEST_SIGN
-static int (*ecdsa_pkey_orig_copy)(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src);
+static int (*ecdsa_pkey_orig_copy)(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src);
 static void (*ecdsa_pkey_orig_cleanup)(EVP_PKEY_CTX *ctx);
 #endif /* HAVE_OPENSSL_DIGEST_SIGN */
 
@@ -405,7 +405,7 @@ ecdsa_ec_key_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
 
 #ifdef HAVE_OPENSSL_DIGEST_SIGN
 static int
-ecdsa_pkey_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
+ecdsa_pkey_copy(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src)
 {
     if (ecdsa_pkey_orig_copy && !ecdsa_pkey_orig_copy(dst, src))
         return 0;
diff --git a/src/tpm2-tss-engine-rsa.c b/src/tpm2-tss-engine-rsa.c
index 41de34e..e7260c2 100644
--- a/src/tpm2-tss-engine-rsa.c
+++ b/src/tpm2-tss-engine-rsa.c
@@ -49,7 +49,7 @@ RSA_METHOD *rsa_methods = NULL;
 #endif /* OPENSSL_VERSION_NUMBER < 0x10100000 */
 
 #ifdef HAVE_OPENSSL_DIGEST_SIGN
-static int (*rsa_pkey_orig_copy)(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src);
+static int (*rsa_pkey_orig_copy)(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src);
 static void (*rsa_pkey_orig_cleanup)(EVP_PKEY_CTX *ctx);
 #endif /* HAVE_OPENSSL_DIGEST_SIGN */
 
@@ -637,7 +637,7 @@ RSA_METHOD rsa_methods = {
 
 #ifdef HAVE_OPENSSL_DIGEST_SIGN
 static int
-rsa_pkey_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
+rsa_pkey_copy(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src)
 {
     if (rsa_pkey_orig_copy && !rsa_pkey_orig_copy(dst, src))
         return 0;