diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index 493f957..3ad2861 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -547,7 +547,7 @@
 		return res;
 
 	coded_len = osmo_conv_encode(code, output, recoded);
-	OSMO_ASSERT(sizeof(recoded) / sizeof(recoded[0]) >= coded_len);
+	OSMO_ASSERT(ARRAY_SIZE(recoded) >= coded_len);
 
 	/* Count bit errors */
 	if (n_errors) {