diff --git a/src/ssl_ckch.c b/src/ssl_ckch.c
index 4a85a5d..1d7f409 100644
--- a/src/ssl_ckch.c
+++ b/src/ssl_ckch.c
@@ -101,9 +101,7 @@
 	struct buffer *sctl;
 
 	if (buf) {
-		tmp.area = buf;
-		tmp.data = strlen(buf);
-		tmp.size = tmp.data + 1;
+		chunk_initstr(&tmp, buf);
 		src = &tmp;
 	} else {
 		fd = open(sctl_path, O_RDONLY);