diff --git a/lucene/core/src/java/org/apache/lucene/index/SegmentMerger.java b/lucene/core/src/java/org/apache/lucene/index/SegmentMerger.java
index 26f9bcbcb25..ea0c7932318 100644
--- a/lucene/core/src/java/org/apache/lucene/index/SegmentMerger.java
+++ b/lucene/core/src/java/org/apache/lucene/index/SegmentMerger.java
@@ -345,11 +345,7 @@ final class SegmentMerger {
   private void mergePerDoc(SegmentWriteState segmentWriteState) throws IOException {
       final PerDocConsumer docsConsumer = codec.docValuesFormat()
           .docsConsumer(new PerDocWriteState(segmentWriteState));
-      // TODO: remove this check when 3.x indexes are no longer supported
-      // (3.x indexes don't have docvalues)
-      if (docsConsumer == null) {
-        return;
-      }
+      assert docsConsumer != null;
       boolean success = false;
       try {
         docsConsumer.merge(mergeState);
@@ -366,11 +362,7 @@ final class SegmentMerger {
   private void mergeNorms(SegmentWriteState segmentWriteState) throws IOException {
     final PerDocConsumer docsConsumer = codec.normsFormat()
         .docsConsumer(new PerDocWriteState(segmentWriteState));
-    // TODO: remove this check when 3.x indexes are no longer supported
-    // (3.x indexes don't have docvalues)
-    if (docsConsumer == null) {
-      return;
-    }
+    assert docsConsumer != null;
     boolean success = false;
     try {
       docsConsumer.merge(mergeState);
diff --git a/lucene/core/src/java/org/apache/lucene/search/similarities/BM25Similarity.java b/lucene/core/src/java/org/apache/lucene/search/similarities/BM25Similarity.java
index a0a4a9f9938..d6979756eb8 100644
--- a/lucene/core/src/java/org/apache/lucene/search/similarities/BM25Similarity.java
+++ b/lucene/core/src/java/org/apache/lucene/search/similarities/BM25Similarity.java
@@ -73,8 +73,8 @@ public class BM25Similarity extends Similarity {
   }
   
   /** The default implementation computes the average as <code>sumTotalTermFreq / maxDoc</code>,
-   * or returns <code>1</code> if the index does not store sumTotalTermFreq (Lucene 3.x indexes
-   * or any field that omits frequency information). */
+   * or returns <code>1</code> if the index does not store sumTotalTermFreq:
+   * any field that omits frequency information). */
   protected float avgFieldLength(CollectionStatistics collectionStats) {
     final long sumTotalTermFreq = collectionStats.sumTotalTermFreq();
     if (sumTotalTermFreq <= 0) {