diff --git a/Objects/structseq.c b/Objects/structseq.c
index 7ad607b..2ab9b52 100644
--- a/Objects/structseq.c
+++ b/Objects/structseq.c
@@ -102,7 +102,8 @@
 	len = PySequence_Length(arg);
 	required_len = REAL_SIZE_TP(type);
 	if (len != required_len) {
-		sprintf(msgbuf,
+		PyOS_snprintf(
+			msgbuf, sizeof(msgbuf),
 			"constructor takes exactly %d arguments (%d given)",
 			required_len,
 			len);