Index: IndexWriter.java
===================================================================
--- IndexWriter.java	(revision 432381)
+++ IndexWriter.java	(working copy)
@@ -681,8 +681,8 @@
 
   /** Merges all RAM-resident segments. */
   private final void flushRamSegments() throws IOException {
-    int minSegment = segmentInfos.size()-1;
-    int docCount = 0;
+    int minSegment = segmentInfos.size()-singleDocSegmentsCount-1;
+    int docCount = singleDocSegmentsCount;
     while (minSegment >= 0 &&
            (segmentInfos.info(minSegment)).dir == ramDirectory) {
       docCount += segmentInfos.info(minSegment).docCount;
@@ -711,12 +711,10 @@
         mergeDocs += si.docCount;
       }
 
-      if (mergeDocs >= targetMergeDocs)	{	  // found a merge to do
+      if (mergeDocs >= targetMergeDocs)	 	  // found a merge to do
         mergeSegments(minSegment+1);
-        singleDocSegmentsCount = 0;
-      } else {
+      else
         break;
-      }
 
       targetMergeDocs *= mergeFactor;		  // increase target size
     }
@@ -749,6 +747,11 @@
         segmentsToDelete.addElement(reader);   // queue segment for deletion
     }
 
+    // update 1-doc segments counter accordin to range of merged segments
+    if (singleDocSegmentsCount>0) {
+      singleDocSegmentsCount = Math.min(singleDocSegmentsCount, segmentInfos.size()-end);
+    }
+
     int mergedDocCount = merger.merge();
 
     if (infoStream != null) {