diff --git a/include/osmocom/coding/gsm0503_parity.h b/include/osmocom/coding/gsm0503_parity.h
index c35477f..bda5f99 100644
--- a/include/osmocom/coding/gsm0503_parity.h
+++ b/include/osmocom/coding/gsm0503_parity.h
@@ -10,15 +10,15 @@
  *  @{
  * \file gsm0503_parity.h */
 
-const struct osmo_crc64gen_code gsm0503_fire_crc40;
-const struct osmo_crc16gen_code gsm0503_cs234_crc16;
-const struct osmo_crc8gen_code gsm0503_mcs_crc8_hdr;
-const struct osmo_crc16gen_code gsm0503_mcs_crc12;
-const struct osmo_crc8gen_code gsm0503_rach_crc6;
-const struct osmo_crc16gen_code gsm0503_sch_crc10;
-const struct osmo_crc8gen_code gsm0503_tch_fr_crc3;
-const struct osmo_crc8gen_code gsm0503_tch_efr_crc8;
-const struct osmo_crc8gen_code gsm0503_amr_crc6;
-const struct osmo_crc16gen_code gsm0503_amr_crc14;
+extern const struct osmo_crc64gen_code gsm0503_fire_crc40;
+extern const struct osmo_crc16gen_code gsm0503_cs234_crc16;
+extern const struct osmo_crc8gen_code gsm0503_mcs_crc8_hdr;
+extern const struct osmo_crc16gen_code gsm0503_mcs_crc12;
+extern const struct osmo_crc8gen_code gsm0503_rach_crc6;
+extern const struct osmo_crc16gen_code gsm0503_sch_crc10;
+extern const struct osmo_crc8gen_code gsm0503_tch_fr_crc3;
+extern const struct osmo_crc8gen_code gsm0503_tch_efr_crc8;
+extern const struct osmo_crc8gen_code gsm0503_amr_crc6;
+extern const struct osmo_crc16gen_code gsm0503_amr_crc14;
 
 /*! @} */