diff --git a/src/asn1helpers.h b/src/asn1helpers.h
index 124df79..bb0f4de 100644
--- a/src/asn1helpers.h
+++ b/src/asn1helpers.h
@@ -7,6 +7,7 @@
 
 void asn1_u32_to_bitstring(BIT_STRING_t *bitstr, uint32_t *buf, uint32_t in);
 void asn1_u24_to_bitstring(BIT_STRING_t *bitstr, uint32_t *buf, uint32_t in);
+int BIT_STRING_fromBuf(BIT_STRING_t *st, const uint8_t *str, unsigned int bit_len);
 void asn1_u16_to_str(OCTET_STRING_t *str, uint16_t *buf, uint16_t in);
 void asn1_u8_to_str(OCTET_STRING_t *str, uint8_t *buf, uint8_t in);
 int asn1_strncpy(char *out, const OCTET_STRING_t *in, size_t n);