diff --git a/lucene/core/src/java/org/apache/lucene/util/fst/FSTCompiler.java b/lucene/core/src/java/org/apache/lucene/util/fst/FSTCompiler.java
index d51c256d48e..df928400cc7 100644
--- a/lucene/core/src/java/org/apache/lucene/util/fst/FSTCompiler.java
+++ b/lucene/core/src/java/org/apache/lucene/util/fst/FSTCompiler.java
@@ -828,7 +828,8 @@ private void freezeTail(int prefixLenPlus1) throws IOException {
       // FSTEnum, Util, etc., have trouble w/ non-final
       // dead-end states:
 
-      // TODO: is node.numArcs == 0 always false?  we no longer prune any nodes from FST:
+      // node.numArcs == 0 happens on last node. But it is final, we still can remove node.numArcs
+      // == 0.
       final boolean isFinal = node.isFinal || node.numArcs == 0;
 
       // this node makes it and we now compile it.  first,