diff --git a/include/osmocom/gsm/gsm_utils.h b/include/osmocom/gsm/gsm_utils.h
index 38a3f6e..de63434 100644
--- a/include/osmocom/gsm/gsm_utils.h
+++ b/include/osmocom/gsm/gsm_utils.h
@@ -115,8 +115,7 @@
 uint8_t gsm_get_octet_len(const uint8_t sept_len);
 int gsm_7bit_decode_n_hdr(char *decoded, size_t n, const uint8_t *user_data, uint8_t length, uint8_t ud_hdr_ind);
 
-unsigned int ms_class_gmsk_dbm(enum gsm_band band, int ms_class);
-
+int ms_class_gmsk_dbm(enum gsm_band band, int ms_class);
 int ms_pwr_ctl_lvl(enum gsm_band band, unsigned int dbm);
 int ms_pwr_dbm(enum gsm_band band, uint8_t lvl);