diff --git a/include/polarssl/asn1.h b/include/polarssl/asn1.h
index dc3f2fe..893292d 100644
--- a/include/polarssl/asn1.h
+++ b/include/polarssl/asn1.h
@@ -53,6 +53,8 @@
 #define POLARSSL_ERR_ASN1_LENGTH_MISMATCH                  -0x0066  /**< Actual length differs from expected length. */
 #define POLARSSL_ERR_ASN1_INVALID_DATA                     -0x0068  /**< Data is invalid. (not used) */
 #define POLARSSL_ERR_ASN1_MALLOC_FAILED                    -0x006A  /**< Memory allocation failed */
+#define POLARSSL_ERR_ASN1_BUF_TOO_SMALL                    -0x006C  /**< Buffer too small when writing ASN.1 data structure. */
+
 /* \} name */
 
 /**
diff --git a/include/polarssl/asn1write.h b/include/polarssl/asn1write.h
index 38f6eea..52b9baa 100644
--- a/include/polarssl/asn1write.h
+++ b/include/polarssl/asn1write.h
@@ -29,8 +29,6 @@
 
 #include "asn1.h"
 
-#define POLARSSL_ERR_ASN1_BUF_TOO_SMALL                    -0x006C  /**< Buffer too small when writing ASN.1 data structure. */
-
 #define ASN1_CHK_ADD(g, f) if( ( ret = f ) < 0 ) return( ret ); else g += ret
 
 int asn1_write_len( unsigned char **p, unsigned char *start, size_t len );
@@ -42,5 +40,7 @@
 int asn1_write_int( unsigned char **p, unsigned char *start, int val );
 int asn1_write_printable_string( unsigned char **p, unsigned char *start,
                                  char *text );
+int asn1_write_ia5_string( unsigned char **p, unsigned char *start,
+                                 char *text );
 
 #endif /* POLARSSL_ASN1_WRITE_H */