diff --git a/src/host/trxcon/include/osmocom/bb/l1sched/l1sched.h b/src/host/trxcon/include/osmocom/bb/l1sched/l1sched.h
index 3c28f4506..f5c45e273 100644
--- a/src/host/trxcon/include/osmocom/bb/l1sched/l1sched.h
+++ b/src/host/trxcon/include/osmocom/bb/l1sched/l1sched.h
@@ -466,8 +466,6 @@ const char *l1sched_burst_mask2str(const uint8_t *mask, int bits);
 size_t l1sched_bad_frame_ind(uint8_t *l2, struct l1sched_lchan_state *lchan);
 
 /* Interleaved TCH/H block TDMA frame mapping */
-uint32_t l1sched_tchh_block_dl_first_fn(enum l1sched_lchan_type chan,
-	uint32_t last_fn, bool facch);
 bool l1sched_tchh_block_map_fn(enum l1sched_lchan_type chan,
 	uint32_t fn, bool ul, bool facch, bool start);
 
diff --git a/src/host/trxcon/src/sched_lchan_tchh.c b/src/host/trxcon/src/sched_lchan_tchh.c
index b0bc566b9..2b4b68250 100644
--- a/src/host/trxcon/src/sched_lchan_tchh.c
+++ b/src/host/trxcon/src/sched_lchan_tchh.c
@@ -149,8 +149,8 @@ bool l1sched_tchh_block_map_fn(enum l1sched_lchan_type chan,
  * @return           either frame number of the first burst,
  *                   or fn=last_fn if calculation failed
  */
-uint32_t l1sched_tchh_block_dl_first_fn(enum l1sched_lchan_type chan,
-	uint32_t last_fn, bool facch)
+static uint32_t tchh_block_dl_first_fn(enum l1sched_lchan_type chan,
+				       uint32_t last_fn, bool facch)
 {
 	uint8_t fn_mf, fn_diff;
 	int i = 0;
@@ -331,7 +331,7 @@ bfi:
 	/* Didn't try to decode, fake measurements */
 	if (n_errors < 0) {
 		lchan->meas_avg = (struct l1sched_meas_set) {
-			.fn = l1sched_tchh_block_dl_first_fn(lchan->type, fn, false),
+			.fn = tchh_block_dl_first_fn(lchan->type, fn, false),
 			.toa256 = 0,
 			.rssi = -110,
 		};