diff --git a/libraries/libldap/tls.c b/libraries/libldap/tls.c
index 97db901a5e..ac7fc6a987 100644
--- a/libraries/libldap/tls.c
+++ b/libraries/libldap/tls.c
@@ -478,7 +478,7 @@ sb_tls_bio_read( BIO *b, char *buf, int len )
 }
 
 static int
-sb_tls_bio_write( BIO *b, char *buf, int len )
+sb_tls_bio_write( BIO *b, const char *buf, int len )
 {
 	struct tls_data		*p;
 	int			ret;
@@ -491,7 +491,7 @@ sb_tls_bio_write( BIO *b, char *buf, int len )
 	if ( p == NULL || p->sbiod == NULL )
 		return 0;
 
-	ret = LBER_SBIOD_WRITE_NEXT( p->sbiod, buf, len );
+	ret = LBER_SBIOD_WRITE_NEXT( p->sbiod, (char *)buf, len );
 
 	BIO_clear_retry_flags( b );
 	if ( ret < 0 && errno == EWOULDBLOCK )
@@ -501,7 +501,7 @@ sb_tls_bio_write( BIO *b, char *buf, int len )
 }
 
 static long
-sb_tls_bio_ctrl( BIO *b, int cmd, long num, char *ptr )
+sb_tls_bio_ctrl( BIO *b, int cmd, long num, void *ptr )
 {
 	if ( cmd == BIO_CTRL_FLUSH ) {
 		/* The OpenSSL library needs this */
@@ -517,7 +517,7 @@ sb_tls_bio_gets( BIO *b, char *buf, int len )
 }
 
 static int
-sb_tls_bio_puts( BIO *b, char *str )
+sb_tls_bio_puts( BIO *b, const char *str )
 {
 	return sb_tls_bio_write( b, str, strlen( str ) );
 }