diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index 5fda4e748..9ec54639f 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -29,7 +29,6 @@ int gsm48_decode_lai(struct gsm48_loc_area_id *lai, uint16_t *mcc,
 		     uint16_t *mnc, uint16_t *lac);
 void gsm48_generate_lai(struct gsm48_loc_area_id *lai48, uint16_t mcc,
 			uint16_t mnc, uint16_t lac);
-void gsm48_encode_classmark1(struct gsm48_classmark1 *cm, uint8_t rev_lv, bool es_ind, bool a5_1, uint8_t rf_pwr);
 int gsm48_generate_mid_from_tmsi(uint8_t *buf, uint32_t tmsi);
 int gsm48_generate_mid_from_imsi(uint8_t *buf, const char *imsi);
 uint8_t gsm48_generate_mid(uint8_t *buf, const char *id, uint8_t mi_type);
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index d9a552734..b58e9e2c5 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -508,22 +508,6 @@ void gsm48_generate_lai(struct gsm48_loc_area_id *lai48, uint16_t mcc,
 	lai48->lac = osmo_htons(lac);
 }
 
-/*! Encode TS 24.008 §10.5.1.5 Mobile Station Classmark 1
- *  \param[out] cm caller-provided memory for output
- *  \param[in] rev_lv Revision level
- *  \param[in] es_ind ES IND "Controlled Early Classmark Sending" option
- *  \param[in] a5_1 A5/1 algorithm supported
- *  \param[in] pwr_lv RF power capability
- */
-void gsm48_encode_classmark1(struct gsm48_classmark1 *cm, uint8_t rev_lv, bool es_ind, bool a5_1, uint8_t rf_pwr)
-{
-	memset(cm, 0, sizeof(*cm));
-	cm->rev_lev = rev_lv;
-	cm->es_ind = es_ind;
-	cm->a5_1 = !a5_1;
-	cm->pwr_lev = rf_pwr;
-}
-
 /*! Decode TS 04.08 Location Area Identifier
  *  \param[in] Location Area Identifier (encoded)
  *  \param[out] mcc Mobile Country Code
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index b6152cec7..7a74718c9 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -245,7 +245,6 @@ gsm48_encode_redirecting;
 gsm48_encode_signal;
 gsm48_encode_ssversion;
 gsm48_encode_useruser;
-gsm48_encode_classmark1;
 gsm48_generate_lai;
 gsm48_generate_mid;
 gsm48_generate_mid_from_imsi;