Index: lucene/core/src/java/org/apache/lucene/index/FieldInfos.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/index/FieldInfos.java	(revision 1518719)
+++ lucene/core/src/java/org/apache/lucene/index/FieldInfos.java	(working copy)
@@ -228,6 +228,11 @@
       nameToNumber.clear();
       docValuesType.clear();
     }
+
+    synchronized void setDocValuesType(int number, String name, DocValuesType dvType) {
+      assert containsConsistent(number, name, dvType);
+      docValuesType.put(name, dvType);
+    }
   }
   
   static final class Builder {
@@ -286,10 +291,13 @@
       } else {
         fi.update(isIndexed, storeTermVector, omitNorms, storePayloads, indexOptions);
 
-        if (docValues != null) {
+        if (!fi.hasDocValues() && docValues != null) {
+          // First time we are seeing doc values type for
+          // this field:
           fi.setDocValuesType(docValues);
-          // must also update docValuesType map so it's aware of this field's DocValueType 
-          globalFieldNumbers.docValuesType.put(name, docValues);
+          // must also update docValuesType map so it's
+          // aware of this field's DocValueType 
+          globalFieldNumbers.setDocValuesType(fi.number, name, docValues);
         }
 
         if (!fi.omitsNorms() && normType != null) {