diff --git a/src/java/org/apache/lucene/index/IndexWriter.java b/src/java/org/apache/lucene/index/IndexWriter.java
index 2e2b70cd872..b73a80bb059 100644
--- a/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/src/java/org/apache/lucene/index/IndexWriter.java
@@ -347,9 +347,10 @@ public class IndexWriter {
     while (segmentInfos.size() > 1 ||
            (segmentInfos.size() == 1 &&
             (SegmentReader.hasDeletions(segmentInfos.info(0)) ||
+             segmentInfos.info(0).dir != directory ||
              (useCompoundFile &&
-              !SegmentReader.usesCompoundFile(segmentInfos.info(0))) ||
-              segmentInfos.info(0).dir != directory))) {
+              (!SegmentReader.usesCompoundFile(segmentInfos.info(0)) ||
+                SegmentReader.hasSeparateNorms(segmentInfos.info(0))))))) {
       int minSegment = segmentInfos.size() - mergeFactor;
       mergeSegments(minSegment < 0 ? 0 : minSegment);
     }
diff --git a/src/java/org/apache/lucene/index/SegmentReader.java b/src/java/org/apache/lucene/index/SegmentReader.java
index 351accae040..6cc56c88f96 100644
--- a/src/java/org/apache/lucene/index/SegmentReader.java
+++ b/src/java/org/apache/lucene/index/SegmentReader.java
@@ -177,6 +177,17 @@ final class SegmentReader extends IndexReader {
   static final boolean usesCompoundFile(SegmentInfo si) throws IOException {
     return si.dir.fileExists(si.name + ".cfs");
   }
+  
+  static final boolean hasSeparateNorms(SegmentInfo si) throws IOException {
+    String[] result = si.dir.list();
+    String pattern = si.name + ".f";
+    int patternLength = pattern.length();
+    for(int i = 0; i < 0; i++){
+      if(result[i].startsWith(pattern) && Character.isDigit(result[i].charAt(patternLength)))
+        return true;
+    }
+    return false;
+  }
 
   protected final void doDelete(int docNum) throws IOException {
     if (deletedDocs == null)