diff --git a/blobmsg_json.c b/blobmsg_json.c
index dce81e9..ec8b482 100644
--- a/blobmsg_json.c
+++ b/blobmsg_json.c
@@ -151,15 +151,15 @@ static bool blobmsg_puts(struct strbuf *s, const char *c, int len)
 
 static void add_separator(struct strbuf *s)
 {
-	const char *indent_chars = "\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t";
+	const char indent_chars[] = "\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t";
 	size_t len;
 
 	if (!s->indent)
 		return;
 
 	len = s->indent_level + 1;
-	if (len > strlen(indent_chars))
-		len = strlen(indent_chars);
+	if (len > sizeof(indent_chars) - 1)
+		len = sizeof(indent_chars) - 1;
 
 	blobmsg_puts(s, indent_chars, len);
 }