diff --git a/lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextSimpleDocValuesFormat.java b/lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextSimpleDocValuesFormat.java
index 19aa562a5fd..bb602f27c5e 100644
--- a/lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextSimpleDocValuesFormat.java
+++ b/lucene/codecs/src/java/org/apache/lucene/codecs/simpletext/SimpleTextSimpleDocValuesFormat.java
@@ -23,8 +23,10 @@ import java.text.DecimalFormat;
 import java.text.DecimalFormatSymbols;
 import java.text.ParseException;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Set;
 
 import org.apache.lucene.codecs.BinaryDocValuesConsumer;
 import org.apache.lucene.codecs.DocValuesArraySource;
@@ -140,15 +142,25 @@ public class SimpleTextSimpleDocValuesFormat extends SimpleDocValuesFormat {
   static class SimpleTextDocValuesWriter extends SimpleDVConsumer {
     final IndexOutput data;
     final BytesRef scratch = new BytesRef();
+
     final int numDocs; // for asserting
+    private final Set<String> fieldsSeen = new HashSet<String>(); // for asserting
     
     SimpleTextDocValuesWriter(Directory dir, SegmentInfo si, IOContext context) throws IOException {
       data = dir.createOutput(IndexFileNames.segmentFileName(si.name, "", "dat"), context);
       numDocs = si.getDocCount();
     }
 
+    // for asserting
+    private boolean fieldSeen(String field) {
+      assert !fieldsSeen.contains(field): "field \"" + field + "\" was added more than once during flush";
+      fieldsSeen.add(field);
+      return true;
+    }
+
     @Override
     public NumericDocValuesConsumer addNumericField(FieldInfo field, final long minValue, long maxValue) throws IOException {
+      assert fieldSeen(field.name);
       writeFieldEntry(field);
       
       // write our minimum value to the .dat, all entries are deltas from that
@@ -189,17 +201,19 @@ public class SimpleTextSimpleDocValuesFormat extends SimpleDocValuesFormat {
           SimpleTextUtil.write(data, s, scratch);
           SimpleTextUtil.writeNewline(data);
           numDocsWritten++;
+          assert numDocsWritten <= numDocs;
         }
 
         @Override
         public void finish() throws IOException {
-          assert numDocs == numDocsWritten;
+          assert numDocs == numDocsWritten: "numDocs=" + numDocs + " numDocsWritten=" + numDocsWritten;
         }
       };
     }
 
     @Override
     public BinaryDocValuesConsumer addBinaryField(FieldInfo field, boolean fixedLength, final int maxLength) throws IOException {
+      assert fieldSeen(field.name);
       writeFieldEntry(field);
       // write maxLength
       SimpleTextUtil.write(data, MAXLENGTH);
@@ -249,6 +263,7 @@ public class SimpleTextSimpleDocValuesFormat extends SimpleDocValuesFormat {
     // nocommit
     @Override
     public SortedDocValuesConsumer addSortedField(FieldInfo field, final int valueCount, boolean fixedLength, final int maxLength) throws IOException {
+      assert fieldSeen(field.name);
       writeFieldEntry(field);
       // write numValues
       SimpleTextUtil.write(data, NUMVALUES);
diff --git a/lucene/core/src/java/org/apache/lucene/codecs/SortedDocValuesConsumer.java b/lucene/core/src/java/org/apache/lucene/codecs/SortedDocValuesConsumer.java
index 4a60f5829de..ca6c9478aba 100644
--- a/lucene/core/src/java/org/apache/lucene/codecs/SortedDocValuesConsumer.java
+++ b/lucene/core/src/java/org/apache/lucene/codecs/SortedDocValuesConsumer.java
@@ -184,6 +184,13 @@ public abstract class SortedDocValuesConsumer {
         for(int docID=0;docID<maxDoc;docID++) {
           if (liveDocs == null || liveDocs.get(docID)) {
             int segOrd = segState.values.getOrd(docID);
+            /*
+            if (segState.segOrdToMergedOrd == null) {
+              BytesRef scratch = new BytesRef();
+              segState.values.lookupOrd(segOrd, scratch);
+              System.out.println("docID=" + docID + " segOrd=" + segOrd + " segValue=" + scratch.utf8ToString());
+            }
+            */
             int mergedOrd = segState.segOrdToMergedOrd[segOrd];
             consumer.addDoc(mergedOrd);
           }
diff --git a/lucene/core/src/java/org/apache/lucene/index/DocFieldProcessorPerField.java b/lucene/core/src/java/org/apache/lucene/index/DocFieldProcessorPerField.java
index 4fafa4772c2..917e16f778f 100644
--- a/lucene/core/src/java/org/apache/lucene/index/DocFieldProcessorPerField.java
+++ b/lucene/core/src/java/org/apache/lucene/index/DocFieldProcessorPerField.java
@@ -17,6 +17,9 @@ package org.apache.lucene.index;
  * limitations under the License.
  */
 
+import java.util.HashMap;
+import java.util.Map;
+
 import org.apache.lucene.util.ArrayUtil;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.Counter;
@@ -43,6 +46,7 @@ final class DocFieldProcessorPerField {
 
   int fieldCount;
   IndexableField[] fields = new IndexableField[1];
+  private final Map<FieldInfo,String> dvFields = new HashMap<FieldInfo,String>();
 
   public DocFieldProcessorPerField(final DocFieldProcessor docFieldProcessor, final FieldInfo fieldInfo) {
     this.consumer = docFieldProcessor.consumer.addField(fieldInfo);
@@ -53,6 +57,7 @@ final class DocFieldProcessorPerField {
   // nocommit make this generic chain through consumer?
   public void addBytesDVField(int docID, BytesRef value) {
     if (bytesDVWriter == null) {
+      verifyField(fieldInfo, "binary");
       bytesDVWriter = new BytesDVWriter(fieldInfo, bytesUsed);
     }
     bytesDVWriter.addValue(docID, value);
@@ -61,6 +66,7 @@ final class DocFieldProcessorPerField {
   // nocommit make this generic chain through consumer?
   public void addSortedBytesDVField(int docID, BytesRef value) {
     if (sortedBytesDVWriter == null) {
+      verifyField(fieldInfo, "sorted");
       sortedBytesDVWriter = new SortedBytesDVWriter(fieldInfo, bytesUsed);
     }
     sortedBytesDVWriter.addValue(docID, value);
@@ -69,6 +75,7 @@ final class DocFieldProcessorPerField {
   // nocommit make this generic chain through consumer?
   public void addNumberDVField(int docID, Number value) {
     if (numberDVWriter == null) {
+      verifyField(fieldInfo, "numeric");
       numberDVWriter = new NumberDVWriter(fieldInfo, bytesUsed);
     }
     numberDVWriter.addValue(docID, value.longValue());
@@ -77,6 +84,7 @@ final class DocFieldProcessorPerField {
   // nocommit make this generic chain through consumer?
   public void addFloatDVField(int docID, Number value) {
     if (numberDVWriter == null) {
+      verifyField(fieldInfo, "numeric");
       numberDVWriter = new NumberDVWriter(fieldInfo, bytesUsed);
     }
     numberDVWriter.addValue(docID, Float.floatToRawIntBits(value.floatValue()));
@@ -85,11 +93,19 @@ final class DocFieldProcessorPerField {
   // nocommit make this generic chain through consumer?
   public void addDoubleDVField(int docID, Number value) {
     if (numberDVWriter == null) {
+      verifyField(fieldInfo, "numeric");
       numberDVWriter = new NumberDVWriter(fieldInfo, bytesUsed);
     }
     numberDVWriter.addValue(docID, Double.doubleToRawLongBits(value.doubleValue()));
   }
 
+  private void verifyField(FieldInfo field, String type) {
+    if (dvFields.containsKey(field)) {
+      throw new IllegalArgumentException("Incompatible DocValues type: field \"" + field.name + "\" changed from " + dvFields.get(field) + " to " + type);
+    }
+    dvFields.put(field, type);
+  }
+
   public void addField(IndexableField field) {
     if (fieldCount == fields.length) {
       int newSize = ArrayUtil.oversize(fieldCount + 1, RamUsageEstimator.NUM_BYTES_OBJECT_REF);
@@ -106,6 +122,9 @@ final class DocFieldProcessorPerField {
     if (bytesDVWriter != null) {
       bytesDVWriter.abort();
     }
+    if (sortedBytesDVWriter != null) {
+      sortedBytesDVWriter.abort();
+    }
     if (numberDVWriter != null) {
       numberDVWriter.abort();
     }
diff --git a/lucene/core/src/test/org/apache/lucene/index/TestDocValuesIndexing.java b/lucene/core/src/test/org/apache/lucene/index/TestDocValuesIndexing.java
index 1f6f2603389..d64122c774c 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestDocValuesIndexing.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestDocValuesIndexing.java
@@ -808,6 +808,33 @@ public class TestDocValuesIndexing extends LuceneTestCase {
     r.close();
     d.close();
   }
+
+  public void testDifferentTypedDocValuesField2() throws Exception {
+    Directory d = newDirectory();
+    RandomIndexWriter w = new RandomIndexWriter(random(), d);
+    Document doc = new Document();
+    // Index doc values are single-valued so we should not
+    // be able to add same field more than once:
+    Field f;
+    doc.add(f = new PackedLongDocValuesField("field", 17));
+    doc.add(new SortedBytesDocValuesField("field", new BytesRef("hello")));
+    try {
+      w.addDocument(doc);
+      fail("didn't hit expected exception");
+    } catch (IllegalArgumentException iae) {
+      // expected
+    }
+
+    doc = new Document();
+    doc.add(f);
+    w.addDocument(doc);
+    w.forceMerge(1);
+    DirectoryReader r = w.getReader();
+    w.close();
+    assertEquals(17, getOnlySegmentReader(r).docValues("field").loadSource().getInt(0));
+    r.close();
+    d.close();
+  }
   
   public void testSortedBytes() throws IOException {
     Type[] types = new Type[] { Type.BYTES_FIXED_SORTED, Type.BYTES_VAR_SORTED };