diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index 9449f4b..5592433 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -1176,7 +1176,7 @@
 	ubit_t iB[456];
 	const ubit_t *hl_hn = gsm0503_pdtch_hl_hn_ubit[3];
 
-	gsm0503_mcs1_dl_interleave(gsm0503_usf2six[usf], hc, dc, iB);
+	gsm0503_mcs1_dl_interleave(gsm0503_usf2twelve_ubit[usf], hc, dc, iB);
 
 	for (i = 0; i < 4; i++) {
 		gsm0503_xcch_burst_map(&iB[i * 114], &bursts[i * 116],