diff --git a/include/mdbprivate.h b/include/mdbprivate.h
index 02204cb..5e6c84c 100644
--- a/include/mdbprivate.h
+++ b/include/mdbprivate.h
@@ -16,8 +16,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#ifndef _mdbprivate_h_
-#define _mdbprivate_h_
+#ifndef MDBPRIVATE_H
+#define MDBPRIVATE_H
 
 #include "mdbtools.h"
 
@@ -30,6 +30,14 @@
 #define g_memdup2 g_memdup
 #endif
 
-void mdb_rc4(unsigned char *key, guint32 key_len, unsigned char *buf, guint32 buf_len);
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+void mdbi_rc4(unsigned char *key, guint32 key_len, unsigned char *buf, guint32 buf_len);
+
+#ifdef __cplusplus
+  }
+#endif
 
 #endif
diff --git a/include/mdbtools.h b/include/mdbtools.h
index e524239..cbe1fd0 100644
--- a/include/mdbtools.h
+++ b/include/mdbtools.h
@@ -648,9 +648,6 @@ void mdb_iconv_init(MdbHandle *mdb);
 void mdb_iconv_close(MdbHandle *mdb);
 const char* mdb_target_charset(MdbHandle *mdb);
 
-/* rc4.c */
-void mdb_rc4(unsigned char *key, guint32 key_len, unsigned char *buf, guint32 buf_len);
-
 /** @}*/
 
 #ifdef __cplusplus
diff --git a/src/libmdb/file.c b/src/libmdb/file.c
index f7cd2d0..b4cb5cc 100644
--- a/src/libmdb/file.c
+++ b/src/libmdb/file.c
@@ -172,7 +172,7 @@ static MdbHandle *mdb_handle_from_stream(FILE *stream, MdbFileFlags flags) {
 	}
 
     guint32 tmp_key = 0x6b39dac7;
-	mdb_rc4(
+	mdbi_rc4(
 		(unsigned char *)&tmp_key,
 		4,
 		mdb->pg_buf + 0x18,
@@ -377,7 +377,7 @@ static ssize_t _mdb_read_pg(MdbHandle *mdb, void *pg_buf, unsigned long pg)
 	if (pg != 0 && mdb->f->db_key != 0)
 	{
 		unsigned int tmp_key = mdb->f->db_key ^ pg;
-		mdb_rc4((unsigned char*)&tmp_key, 4, pg_buf, mdb->fmt->pg_size);
+		mdbi_rc4((unsigned char*)&tmp_key, 4, pg_buf, mdb->fmt->pg_size);
 	}
 
 	return mdb->fmt->pg_size;
diff --git a/src/libmdb/rc4.c b/src/libmdb/rc4.c
index 2956d17..5596736 100644
--- a/src/libmdb/rc4.c
+++ b/src/libmdb/rc4.c
@@ -18,7 +18,7 @@
 
 #include "mdbprivate.h"
 
-typedef struct _RC4_KEY
+typedef struct
 {
 	unsigned char state[256];
 	unsigned char x;
@@ -78,7 +78,7 @@ static void RC4(RC4_KEY *key, int buffer_len, unsigned char * buff)
 	key->y = y;
 }
 
-void mdb_rc4(unsigned char *key, guint32 key_len, unsigned char *buf, guint32 buf_len) {
+void mdbi_rc4(unsigned char *key, guint32 key_len, unsigned char *buf, guint32 buf_len) {
     RC4_KEY rc4_key;
     RC4_set_key(&rc4_key, key_len, key);
     RC4(&rc4_key, buf_len, buf);
diff --git a/src/libmdb/write.c b/src/libmdb/write.c
index 1d791ab..6ae073a 100644
--- a/src/libmdb/write.c
+++ b/src/libmdb/write.c
@@ -84,7 +84,7 @@ mdb_write_pg(MdbHandle *mdb, unsigned long pg)
 	{
 		buf = g_memdup2(mdb->pg_buf, mdb->fmt->pg_size);
 		unsigned int tmp_key = mdb->f->db_key ^ pg;
-		mdb_rc4((unsigned char*)&tmp_key, 4, buf, mdb->fmt->pg_size);
+		mdbi_rc4((unsigned char*)&tmp_key, 4, buf, mdb->fmt->pg_size);
 	}
 
 	len = fwrite(buf, 1, mdb->fmt->pg_size, mdb->f->stream);