Index: contrib/analyzers/common/src/test/org/apache/lucene/analysis/ngram/NGramTokenFilterTest.java
===================================================================
--- contrib/analyzers/common/src/test/org/apache/lucene/analysis/ngram/NGramTokenFilterTest.java	(revision 1067853)
+++ contrib/analyzers/common/src/test/org/apache/lucene/analysis/ngram/NGramTokenFilterTest.java	(working copy)
@@ -17,6 +17,8 @@
  * limitations under the License.
  */
 
+import org.apache.lucene.analysis.MappingCharFilter;
+import org.apache.lucene.analysis.NormalizeCharMap;
 import org.apache.lucene.analysis.TokenStream;
 import org.apache.lucene.analysis.WhitespaceTokenizer;
 import org.apache.lucene.analysis.BaseTokenStreamTestCase;
@@ -92,4 +94,12 @@
       tokenizer.reset(new StringReader("abcde"));
       assertTokenStreamContents(filter, new String[]{"a","b","c","d","e"}, new int[]{0,1,2,3,4}, new int[]{1,2,3,4,5});
     }
+    
+    public void testCorrectOffsetWithMappingChar() throws Exception {
+    	NormalizeCharMap map = new NormalizeCharMap();
+    	map.add("c", "zzz");
+        WhitespaceTokenizer tokenizer = new WhitespaceTokenizer(new MappingCharFilter(map, new StringReader("abcde")));
+        NGramTokenFilter filter = new NGramTokenFilter(tokenizer, 1, 1);
+        assertTokenStreamContents(filter, new String[]{"a","b","z","z","z","d","e"}, new int[]{0,1,2,3,4,5,5}, new int[]{1,2,3,4,5,5,5});
+    }
 }
Index: contrib/analyzers/common/src/java/org/apache/lucene/analysis/ngram/NGramTokenFilter.java
===================================================================
--- contrib/analyzers/common/src/java/org/apache/lucene/analysis/ngram/NGramTokenFilter.java	(revision 1067853)
+++ contrib/analyzers/common/src/java/org/apache/lucene/analysis/ngram/NGramTokenFilter.java	(working copy)
@@ -39,6 +39,7 @@
   private int curGramSize;
   private int curPos;
   private int tokStart;
+  private int tokEnd;
   
   private TermAttribute termAtt;
   private OffsetAttribute offsetAtt;
@@ -84,13 +85,14 @@
           curGramSize = minGram;
           curPos = 0;
           tokStart = offsetAtt.startOffset();
+          tokEnd = offsetAtt.endOffset();
         }
       }
       while (curGramSize <= maxGram) {
         while (curPos+curGramSize <= curTermLength) {     // while there is input
           clearAttributes();
           termAtt.setTermBuffer(curTermBuffer, curPos, curGramSize);
-          offsetAtt.setOffset(tokStart + curPos, tokStart + curPos + curGramSize);
+          offsetAtt.setOffset(Math.min(tokStart + curPos, tokEnd), Math.min(tokStart + curPos + curGramSize, tokEnd));
           curPos++;
           return true;
         }