diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index 1ef6393..3fd440f 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -1860,7 +1860,7 @@
 			return -1;
 		}
 
-		return 23;
+		return GSM_MACBLOCK_LEN;
 	}
 
 	osmo_conv_decode_ber(&gsm0503_tch_fr, cB, conv, n_errors, n_bits_total);