diff --git a/lucene/core/src/java/org/apache/lucene/codecs/lucene3x/Lucene3xSegmentInfoReader.java b/lucene/core/src/java/org/apache/lucene/codecs/lucene3x/Lucene3xSegmentInfoReader.java
index 225be4238ac..27f5d3d27ed 100644
--- a/lucene/core/src/java/org/apache/lucene/codecs/lucene3x/Lucene3xSegmentInfoReader.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/lucene3x/Lucene3xSegmentInfoReader.java
@@ -251,22 +251,10 @@ public class Lucene3xSegmentInfoReader extends SegmentInfoReader {
 
     final String version = input.readString();
 
-    // nocommit: we ignore this and use the incoming arg: don't write this
-    input.readString();
-
     final int docCount = input.readInt();
-    // nocommit: dont write this
-    final long delGen = input.readLong();
     
     final Map<String,String> attributes = input.readStringStringMap();
 
-    // pre-4.0 indexes write a byte if there is a single norms file
-    byte b = input.readByte();
-
-    //System.out.println("version=" + version + " name=" + name + " docCount=" + docCount + " delGen=" + delGen + " dso=" + docStoreOffset + " dss=" + docStoreSegment + " dssCFs=" + docStoreIsCompoundFile + " b=" + b + " format=" + format);
-
-    // nocommit: don't write this
-    assert 1 == b : "expected 1 but was: "+ b;
     final int numNormGen = input.readInt();
     final Map<Integer,Long> normGen;
     if (numNormGen == SegmentInfo.NO) {
@@ -279,17 +267,8 @@ public class Lucene3xSegmentInfoReader extends SegmentInfoReader {
     }
     final boolean isCompoundFile = input.readByte() == SegmentInfo.YES;
 
-    final int delCount = input.readInt();
-    assert delCount <= docCount;
-
-    // nocommit: unused, dont write this
-    final boolean hasProx = input.readByte() == 1;
-
     final Map<String,String> diagnostics = input.readStringStringMap();
 
-    // nocommit: unused, dont write this
-    final int hasVectors = input.readByte();
-
     final Set<String> files = input.readStringSet();
 
     // nocommit: convert normgen into attributes?
diff --git a/lucene/core/src/java/org/apache/lucene/index/SegmentInfos.java b/lucene/core/src/java/org/apache/lucene/index/SegmentInfos.java
index a5a2018491e..77a82fe372a 100644
--- a/lucene/core/src/java/org/apache/lucene/index/SegmentInfos.java
+++ b/lucene/core/src/java/org/apache/lucene/index/SegmentInfos.java
@@ -423,15 +423,9 @@ public final class SegmentInfos implements Cloneable, Iterable<SegmentInfoPerCom
       assert si.getCodec() instanceof Lucene3xCodec : "broken test, trying to mix preflex with other codecs";
       // Write the Lucene version that created this segment, since 3.1
       output.writeString(si.getVersion());
-      output.writeString(si.name);
       output.writeInt(si.getDocCount());
 
-      // NOTE: a lie
-      output.writeLong(0L);
-
       output.writeStringStringMap(si.attributes());
-      // pre-4.0 indexes write a byte if there is a single norms file
-      output.writeByte((byte) 1);
 
       Map<Integer,Long> normGen = si.getNormGen();
       if (normGen == null) {
@@ -444,15 +438,7 @@ public final class SegmentInfos implements Cloneable, Iterable<SegmentInfoPerCom
       }
 
       output.writeByte((byte) (si.getUseCompoundFile() ? SegmentInfo.YES : SegmentInfo.NO));
-
-      // NOTE: a lie
-      output.writeInt(0);
-
-      // hasProx (lie):
-      output.writeByte((byte) 1);
       output.writeStringStringMap(si.getDiagnostics());
-      // hasVectors (lie):
-      output.writeByte((byte) 1);
       output.writeStringSet(si.files());
 
       success = true;