diff --git a/dir.c b/dir.c
index 2ccd4db664..ba4a51c296 100644
--- a/dir.c
+++ b/dir.c
@@ -2738,54 +2738,49 @@ static int read_one_dir(struct untracked_cache_dir **untracked_,
 			struct read_data *rd)
 {
 	struct untracked_cache_dir ud, *untracked;
-	const unsigned char *next, *data = rd->data, *end = rd->end;
+	const unsigned char *data = rd->data, *end = rd->end;
+	const unsigned char *eos;
 	unsigned int value;
-	int i, len;
+	int i;
 
 	memset(&ud, 0, sizeof(ud));
 
-	next = data;
-	value = decode_varint(&next);
-	if (next > end)
+	value = decode_varint(&data);
+	if (data > end)
 		return -1;
 	ud.recurse	   = 1;
 	ud.untracked_alloc = value;
 	ud.untracked_nr	   = value;
 	if (ud.untracked_nr)
 		ALLOC_ARRAY(ud.untracked, ud.untracked_nr);
-	data = next;
 
-	next = data;
-	ud.dirs_alloc = ud.dirs_nr = decode_varint(&next);
-	if (next > end)
+	ud.dirs_alloc = ud.dirs_nr = decode_varint(&data);
+	if (data > end)
 		return -1;
 	ALLOC_ARRAY(ud.dirs, ud.dirs_nr);
-	data = next;
 
-	len = strlen((const char *)data);
-	next = data + len + 1;
-	if (next > rd->end)
+	eos = memchr(data, '\0', end - data);
+	if (!eos || eos == end)
 		return -1;
-	*untracked_ = untracked = xmalloc(st_add3(sizeof(*untracked), len, 1));
+
+	*untracked_ = untracked = xmalloc(st_add3(sizeof(*untracked), eos - data, 1));
 	memcpy(untracked, &ud, sizeof(ud));
-	memcpy(untracked->name, data, len + 1);
-	data = next;
+	memcpy(untracked->name, data, eos - data + 1);
+	data = eos + 1;
 
 	for (i = 0; i < untracked->untracked_nr; i++) {
-		len = strlen((const char *)data);
-		next = data + len + 1;
-		if (next > rd->end)
+		eos = memchr(data, '\0', end - data);
+		if (!eos || eos == end)
 			return -1;
-		untracked->untracked[i] = xstrdup((const char*)data);
-		data = next;
+		untracked->untracked[i] = xmemdupz(data, eos - data);
+		data = eos + 1;
 	}
 
 	rd->ucd[rd->index++] = untracked;
 	rd->data = data;
 
 	for (i = 0; i < untracked->dirs_nr; i++) {
-		len = read_one_dir(untracked->dirs + i, rd);
-		if (len < 0)
+		if (read_one_dir(untracked->dirs + i, rd) < 0)
 			return -1;
 	}
 	return 0;