diff --git a/diff2.js b/diff2.js
index 1ec8ad3..1d7e255 100644
--- a/diff2.js
+++ b/diff2.js
@@ -951,6 +951,12 @@ console.log(valueDiff(
 
 //*/
 
+// XXX BUG: no change is detected here...
+console.log(valueDiff(
+	[,,,1],
+	[1],
+))
+