diff --git a/src/dat/nbt.c b/src/dat/nbt.c
index f1d71d1..267d296 100644
--- a/src/dat/nbt.c
+++ b/src/dat/nbt.c
@@ -215,6 +215,6 @@ const u8 *nbt_nexttag(const u8 *restrict buf)
 	tag = buf;
 	do {
 		tag = nexttag(tag, &dpt, lens, tags);
-	} while (dpt > 0);
+	} while (tag && dpt > 0);
 	return tag;
 }