diff --git a/include/polarssl/asn1write.h b/include/polarssl/asn1write.h
index 6e4a257..9b98afe 100644
--- a/include/polarssl/asn1write.h
+++ b/include/polarssl/asn1write.h
@@ -52,6 +52,8 @@
                           const unsigned char *buf, size_t bits );
 int asn1_write_octet_string( unsigned char **p, unsigned char *start,
                              const unsigned char *buf, size_t size );
+int asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
+                           const unsigned char *buf, size_t size );
 
 #ifdef __cplusplus
 }