Problem with OpenSSL ERR_get_error_line_data()

/*
(~/temp) - (irotas@pts/2.jake) - (12:28:50)
-$ g++ --version
g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


(~/temp) - (irotas@pts/2.jake) - (12:28:53)
-$ g++ -c sslerr.cpp -lssl -lcrypto
sslerr.cpp: In function 'int main(int, char**)':
sslerr.cpp:14:9: error: invalid conversion from 'const void*' to 'void*' [-fpermissive]
/usr/include/openssl/crypto.h:494:6: error:   initializing argument 1 of 'void CRYPTO_free(void*)' [-fpermissive]
*/

#include <openssl/err.h>

int main(int argc, char** argv)
{
    const char* file = (char*)0;
    int line = 0;
    const char* data = (char*)0;
    int flags = 0;

    unsigned long rc = ERR_get_error_line_data(&file, &line, &data, &flags);

    if (flags & ERR_TXT_MALLOCED)
    {
        OPENSSL_free(data);
    }

    return 0;
}