diff --git a/src/opcua/x509/openssl_symbols.cpp b/src/opcua/x509/openssl_symbols.cpp
index e4807e0c8..0ad1396b1 100644
--- a/src/opcua/x509/openssl_symbols.cpp
+++ b/src/opcua/x509/openssl_symbols.cpp
@@ -273,7 +273,7 @@ DEFINEFUNC3(int, BIO_read, BIO *a, a, void *b, b, int c, c, return -1, return)
 DEFINEFUNC3(int, BIO_write, BIO *a, a, const void *b, b, int c, c, return -1, return)
 DEFINEFUNC(int, BN_num_bits, const BIGNUM *a, a, return 0, return)
 DEFINEFUNC2(BN_ULONG, BN_mod_word, const BIGNUM *a, a, BN_ULONG w, w, return static_cast<BN_ULONG>(-1), return)
-DEFINEFUNC2(int, BN_set_word, const BIGNUM *a, a, BN_ULONG w, w, return 0, return)
+DEFINEFUNC2(int, BN_set_word, BIGNUM *a, a, BN_ULONG w, w, return 0, return)
 DEFINEFUNC(BIGNUM *, BN_new, void, DUMMYARG, return nullptr, return)
 DEFINEFUNC(void, BN_clear, BIGNUM *bignum, bignum, return, return)
 DEFINEFUNC(void, BN_free, BIGNUM *bignum, bignum, return, return)
@@ -339,7 +339,7 @@ DEFINEFUNC4(DH *, PEM_read_bio_DHparams, BIO *a, a, DH **b, b, pem_password_cb *
 DEFINEFUNC7(int, PEM_write_bio_DSAPrivateKey, BIO *a, a, DSA *b, b, const EVP_CIPHER *c, c, unsigned char *d, d, int e, e, pem_password_cb *f, f, void *g, g, return 0, return)
 DEFINEFUNC7(int, PEM_write_bio_RSAPrivateKey, BIO *a, a, RSA *b, b, const EVP_CIPHER *c, c, unsigned char *d, d, int e, e, pem_password_cb *f, f, void *g, g, return 0, return)
 DEFINEFUNC7(int, PEM_write_bio_PrivateKey, BIO *a, a, EVP_PKEY *b, b, const EVP_CIPHER *c, c, unsigned char *d, d, int e, e, pem_password_cb *f, f, void *g, g, return 0, return)
-DEFINEFUNC7(int, PEM_write_bio_PKCS8PrivateKey, BIO *a, a, EVP_PKEY *b, b, const EVP_CIPHER *c, c, unsigned char *d, d, int e, e, pem_password_cb *f, f, void *g, g, return 0, return)
+DEFINEFUNC7(int, PEM_write_bio_PKCS8PrivateKey, BIO *a, a, EVP_PKEY *b, b, const EVP_CIPHER *c, c, char *d, d, int e, e, pem_password_cb *f, f, void *g, g, return 0, return)
 #ifndef OPENSSL_NO_EC
 DEFINEFUNC7(int, PEM_write_bio_ECPrivateKey, BIO *a, a, EC_KEY *b, b, const EVP_CIPHER *c, c, unsigned char *d, d, int e, e, pem_password_cb *f, f, void *g, g, return 0, return)
 #endif
diff --git a/src/opcua/x509/openssl_symbols_p.h b/src/opcua/x509/openssl_symbols_p.h
index 7c51e0871..c0ba6774e 100644
--- a/src/opcua/x509/openssl_symbols_p.h
+++ b/src/opcua/x509/openssl_symbols_p.h
@@ -385,7 +385,7 @@ int q_PEM_write_bio_RSAPrivateKey(BIO *a, RSA *b, const EVP_CIPHER *c, unsigned
                                   int e, pem_password_cb *f, void *g);
 int q_PEM_write_bio_PrivateKey(BIO *a, EVP_PKEY *b, const EVP_CIPHER *c, unsigned char *d,
                                int e, pem_password_cb *f, void *g);
-int q_PEM_write_bio_PKCS8PrivateKey(BIO *a, EVP_PKEY *b, const EVP_CIPHER *c, unsigned char *d,
+int q_PEM_write_bio_PKCS8PrivateKey(BIO *a, EVP_PKEY *b, const EVP_CIPHER *c, char *d,
                                int e, pem_password_cb *f, void *g);
 #ifndef OPENSSL_NO_EC
 int q_PEM_write_bio_ECPrivateKey(BIO *a, EC_KEY *b, const EVP_CIPHER *c, unsigned char *d,
diff --git a/src/opcua/x509/qopcuakeypair_openssl.cpp b/src/opcua/x509/qopcuakeypair_openssl.cpp
index 0f0df5c9f..6c475f530 100644
--- a/src/opcua/x509/qopcuakeypair_openssl.cpp
+++ b/src/opcua/x509/qopcuakeypair_openssl.cpp
@@ -240,7 +240,7 @@ QByteArray QOpcUaKeyPairPrivate::privateKeyToByteArray(QOpcUaKeyPair::Cipher cip
     }
 
     if (0 == q_PEM_write_bio_PKCS8PrivateKey(bio, m_keyData, enc,
-                                         enc ? (unsigned char*)password.toUtf8().constData() : NULL,
+                                         enc ? (char*)password.toUtf8().constData() : NULL,
                                          enc ? password.length() : 0,
                                          NULL /* callback */, NULL /* userdata */)) {
         qCWarning(lcSsl) << "Failed to write private key:" << getOpenSslError();