diff --git a/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50LiveDocsFormat.java b/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50LiveDocsFormat.java
index 612bb9b1779..55b0844b49f 100644
--- a/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50LiveDocsFormat.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50LiveDocsFormat.java
@@ -22,6 +22,7 @@ import java.util.Collection;
 
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.LiveDocsFormat;
+import org.apache.lucene.index.CorruptIndexException;
 import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentCommitInfo;
 import org.apache.lucene.store.ChecksumIndexInput;
@@ -40,9 +41,10 @@ import org.apache.lucene.util.MutableBits;
  * deletions.</p>
  * <p>Although per-segment, this file is maintained exterior to compound segment
  * files.</p>
- * <p>Deletions (.liv) --&gt; SegmentHeader,Bits</p>
+ * <p>Deletions (.liv) --&gt; SegmentHeader,Generation,Bits</p>
  * <ul>
  *   <li>SegmentHeader --&gt; {@link CodecUtil#writeSegmentHeader SegmentHeader}</li>
+ *   <li>Generation --&gt; {@link DataOutput#writeLong Int64}
  *   <li>Bits --&gt; &lt;{@link DataOutput#writeLong Int64}&gt; <sup>LongCount</sup></li>
  * </ul>
  */
@@ -73,12 +75,17 @@ public class Lucene50LiveDocsFormat extends LiveDocsFormat {
 
   @Override
   public Bits readLiveDocs(Directory dir, SegmentCommitInfo info, IOContext context) throws IOException {
-    String name = IndexFileNames.fileNameFromGeneration(info.info.name, EXTENSION, info.getDelGen());
+    long gen = info.getDelGen();
+    String name = IndexFileNames.fileNameFromGeneration(info.info.name, EXTENSION, gen);
     final int length = info.info.getDocCount();
     try (ChecksumIndexInput input = dir.openChecksumInput(name, context)) {
       Throwable priorE = null;
       try {
         CodecUtil.checkSegmentHeader(input, CODEC_NAME, VERSION_START, VERSION_CURRENT, info.info.getId());
+        long filegen = input.readLong();
+        if (gen != filegen) {
+          throw new CorruptIndexException("file mismatch, expected generation=" + gen + ", got=" + filegen, input);
+        }
         long data[] = new long[FixedBitSet.bits2words(length)];
         for (int i = 0; i < data.length; i++) {
           data[i] = input.readLong();
@@ -95,10 +102,12 @@ public class Lucene50LiveDocsFormat extends LiveDocsFormat {
 
   @Override
   public void writeLiveDocs(MutableBits bits, Directory dir, SegmentCommitInfo info, int newDelCount, IOContext context) throws IOException {
-    String name = IndexFileNames.fileNameFromGeneration(info.info.name, EXTENSION, info.getNextDelGen());
+    long gen = info.getNextDelGen();
+    String name = IndexFileNames.fileNameFromGeneration(info.info.name, EXTENSION, gen);
     long data[] = ((FixedBitSet) bits).getBits();
     try (IndexOutput output = dir.createOutput(name, context)) {
       CodecUtil.writeSegmentHeader(output, CODEC_NAME, VERSION_CURRENT, info.info.getId());
+      output.writeLong(gen);
       for (int i = 0; i < data.length; i++) {
         output.writeLong(data[i]);
       }
diff --git a/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50SegmentInfoWriter.java b/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50SegmentInfoWriter.java
index ab407d9221c..70e66ea86e0 100755
--- a/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50SegmentInfoWriter.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/lucene50/Lucene50SegmentInfoWriter.java
@@ -18,6 +18,7 @@ package org.apache.lucene.codecs.lucene50;
  */
 
 import java.io.IOException;
+import java.util.Set;
 
 import org.apache.lucene.codecs.CodecUtil;
 import org.apache.lucene.codecs.SegmentInfoWriter;
@@ -28,6 +29,7 @@ import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.IOContext;
 import org.apache.lucene.store.IndexOutput;
 import org.apache.lucene.util.IOUtils;
+import org.apache.lucene.util.StringHelper;
 import org.apache.lucene.util.Version;
 
 /**
@@ -48,10 +50,8 @@ public class Lucene50SegmentInfoWriter extends SegmentInfoWriter {
     final String fileName = IndexFileNames.segmentFileName(si.name, "", Lucene50SegmentInfoFormat.SI_EXTENSION);
     si.addFile(fileName);
 
-    final IndexOutput output = dir.createOutput(fileName, ioContext);
-
     boolean success = false;
-    try {
+    try (IndexOutput output = dir.createOutput(fileName, ioContext)) {
       CodecUtil.writeHeader(output, Lucene50SegmentInfoFormat.CODEC_NAME, Lucene50SegmentInfoFormat.VERSION_CURRENT);
       Version version = si.getVersion();
       if (version.major < 5) {
@@ -63,18 +63,24 @@ public class Lucene50SegmentInfoWriter extends SegmentInfoWriter {
 
       output.writeByte((byte) (si.getUseCompoundFile() ? SegmentInfo.YES : SegmentInfo.NO));
       output.writeStringStringMap(si.getDiagnostics());
-      output.writeStringSet(si.files());
+      Set<String> files = si.files();
+      for (String file : files) {
+        if (!IndexFileNames.parseSegmentName(file).equals(si.name)) {
+          throw new IllegalArgumentException("invalid files: expected segment=" + si.name + ", got=" + files);
+        }
+      }
+      output.writeStringSet(files);
       byte[] id = si.getId();
+      if (id.length != StringHelper.ID_LENGTH) {
+        throw new IllegalArgumentException("invalid id, got=" + StringHelper.idToString(id));
+      }
       output.writeBytes(id, 0, id.length);
       CodecUtil.writeFooter(output);
       success = true;
     } finally {
       if (!success) {
-        IOUtils.closeWhileHandlingException(output);
         // TODO: are we doing this outside of the tracking wrapper? why must SIWriter cleanup like this?
         IOUtils.deleteFilesIgnoringExceptions(si.dir, fileName);
-      } else {
-        output.close();
       }
     }
   }