diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 47f8cdb207f1..74273e638c0d 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1658,8 +1658,12 @@ static void gsm_queue(struct gsm_mux *gsm)
 
 	if ((gsm->control & ~PF) == UI)
 		gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
-	/* generate final CRC with received FCS */
-	gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
+	if (gsm->encoding == 0){
+		/* WARNING: gsm->received_fcs is used for gsm->encoding = 0 only.
+		            In this case it contain the last piece of data
+		            required to generate final CRC */
+		gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
+	}
 	if (gsm->fcs != GOOD_FCS) {
 		gsm->bad_fcs++;
 		if (debug & 4)