diff --git a/moshi/src/main/java/com/squareup/moshi/BufferedSinkJsonWriter.java b/moshi/src/main/java/com/squareup/moshi/BufferedSinkJsonWriter.java
index cd5a834..9464dc5 100644
--- a/moshi/src/main/java/com/squareup/moshi/BufferedSinkJsonWriter.java
+++ b/moshi/src/main/java/com/squareup/moshi/BufferedSinkJsonWriter.java
@@ -62,8 +62,6 @@ final class BufferedSinkJsonWriter extends JsonWriter {
 
   private String deferredName;
 
-  private boolean promoteNameToValue;
-
   BufferedSinkJsonWriter(BufferedSink sink) {
     if (sink == null) {
       throw new NullPointerException("sink == null");
@@ -92,7 +90,7 @@ final class BufferedSinkJsonWriter extends JsonWriter {
   }
 
   @Override public JsonWriter endObject() throws IOException {
-    promoteNameToValue = false;
+    promoteValueToName = false;
     return close(EMPTY_OBJECT, NONEMPTY_OBJECT, "}");
   }
 
@@ -143,7 +141,7 @@ final class BufferedSinkJsonWriter extends JsonWriter {
     }
     deferredName = name;
     pathNames[stackSize - 1] = name;
-    promoteNameToValue = false;
+    promoteValueToName = false;
     return this;
   }
 
@@ -159,7 +157,7 @@ final class BufferedSinkJsonWriter extends JsonWriter {
     if (value == null) {
       return nullValue();
     }
-    if (promoteNameToValue) {
+    if (promoteValueToName) {
       return name(value);
     }
     writeDeferredName();
@@ -203,7 +201,7 @@ final class BufferedSinkJsonWriter extends JsonWriter {
     if (!lenient && (Double.isNaN(value) || Double.isInfinite(value))) {
       throw new IllegalArgumentException("Numeric values must be finite, but was " + value);
     }
-    if (promoteNameToValue) {
+    if (promoteValueToName) {
       return name(Double.toString(value));
     }
     writeDeferredName();
@@ -214,7 +212,7 @@ final class BufferedSinkJsonWriter extends JsonWriter {
   }
 
   @Override public JsonWriter value(long value) throws IOException {
-    if (promoteNameToValue) {
+    if (promoteValueToName) {
       return name(Long.toString(value));
     }
     writeDeferredName();
@@ -234,7 +232,7 @@ final class BufferedSinkJsonWriter extends JsonWriter {
         && (string.equals("-Infinity") || string.equals("Infinity") || string.equals("NaN"))) {
       throw new IllegalArgumentException("Numeric values must be finite, but was " + value);
     }
-    if (promoteNameToValue) {
+    if (promoteValueToName) {
       return name(string);
     }
     writeDeferredName();
@@ -369,12 +367,4 @@ final class BufferedSinkJsonWriter extends JsonWriter {
         throw new IllegalStateException("Nesting problem.");
     }
   }
-
-  @Override void promoteNameToValue() throws IOException {
-    int context = peekScope();
-    if (context != NONEMPTY_OBJECT && context != EMPTY_OBJECT) {
-      throw new IllegalStateException("Nesting problem.");
-    }
-    promoteNameToValue = true;
-  }
 }
diff --git a/moshi/src/main/java/com/squareup/moshi/JsonWriter.java b/moshi/src/main/java/com/squareup/moshi/JsonWriter.java
index e178760..c017995 100644
--- a/moshi/src/main/java/com/squareup/moshi/JsonWriter.java
+++ b/moshi/src/main/java/com/squareup/moshi/JsonWriter.java
@@ -20,6 +20,9 @@ import java.io.Flushable;
 import java.io.IOException;
 import okio.BufferedSink;
 
+import static com.squareup.moshi.JsonScope.EMPTY_OBJECT;
+import static com.squareup.moshi.JsonScope.NONEMPTY_OBJECT;
+
 /**
  * Writes a JSON (<a href="http://www.ietf.org/rfc/rfc7159.txt">RFC 7159</a>)
  * encoded value to a stream, one token at a time. The stream includes both
@@ -131,6 +134,7 @@ public abstract class JsonWriter implements Closeable, Flushable {
   String indent;
   boolean lenient;
   boolean serializeNulls;
+  boolean promoteValueToName;
 
   /** Returns a new instance that writes a JSON-encoded stream to {@code sink}. */
   public static JsonWriter of(BufferedSink sink) {
@@ -313,10 +317,16 @@ public abstract class JsonWriter implements Closeable, Flushable {
   public abstract JsonWriter value(Number value) throws IOException;
 
   /**
-   * Changes the reader to treat the next string value as a name. This is useful for map adapters so
-   * that arbitrary type adapters can use {@link #value(String)} to write a name value.
+   * Changes the writer to treat the next value as a string name. This is useful for map adapters so
+   * that arbitrary type adapters can use {@link #value} to write a name value.
    */
-  abstract void promoteNameToValue() throws IOException;
+  final void promoteValueToName() throws IOException {
+    int context = peekScope();
+    if (context != NONEMPTY_OBJECT && context != EMPTY_OBJECT) {
+      throw new IllegalStateException("Nesting problem.");
+    }
+    promoteValueToName = true;
+  }
 
   /**
    * Returns a <a href="http://goessner.net/articles/JsonPath/">JsonPath</a> to
diff --git a/moshi/src/main/java/com/squareup/moshi/MapJsonAdapter.java b/moshi/src/main/java/com/squareup/moshi/MapJsonAdapter.java
index 3158108..8cf784d 100644
--- a/moshi/src/main/java/com/squareup/moshi/MapJsonAdapter.java
+++ b/moshi/src/main/java/com/squareup/moshi/MapJsonAdapter.java
@@ -52,7 +52,7 @@ final class MapJsonAdapter<K, V> extends JsonAdapter<Map<K, V>> {
       if (entry.getKey() == null) {
         throw new JsonDataException("Map key is null at " + writer.getPath());
       }
-      writer.promoteNameToValue();
+      writer.promoteValueToName();
       keyAdapter.toJson(writer, entry.getKey());
       valueAdapter.toJson(writer, entry.getValue());
     }
diff --git a/moshi/src/main/java/com/squareup/moshi/ObjectJsonReader.java b/moshi/src/main/java/com/squareup/moshi/ObjectJsonReader.java
index 8f16fec..0f30d88 100644
--- a/moshi/src/main/java/com/squareup/moshi/ObjectJsonReader.java
+++ b/moshi/src/main/java/com/squareup/moshi/ObjectJsonReader.java
@@ -273,10 +273,10 @@ final class ObjectJsonReader extends JsonReader {
   }
 
   @Override void promoteNameToValue() throws IOException {
-    Map.Entry<?, ?> peeked = require(Map.Entry.class, Token.NAME);
-
-    push(peeked.getKey());
-    stack[stackSize - 2] = peeked.getValue();
+    if (hasNext()) {
+      String name = nextName();
+      push(name);
+    }
   }
 
   @Override public void close() throws IOException {
diff --git a/moshi/src/main/java/com/squareup/moshi/ObjectJsonWriter.java b/moshi/src/main/java/com/squareup/moshi/ObjectJsonWriter.java
index a4b7c53..237d462 100644
--- a/moshi/src/main/java/com/squareup/moshi/ObjectJsonWriter.java
+++ b/moshi/src/main/java/com/squareup/moshi/ObjectJsonWriter.java
@@ -79,6 +79,7 @@ final class ObjectJsonWriter extends JsonWriter {
     if (peekScope() != EMPTY_OBJECT || deferredName != null) {
       throw new IllegalStateException("Nesting problem.");
     }
+    promoteValueToName = false;
     stackSize--;
     stack[stackSize] = null;
     pathNames[stackSize] = null; // Free the last path name so that it can be garbage collected!
@@ -96,12 +97,16 @@ final class ObjectJsonWriter extends JsonWriter {
     if (peekScope() != EMPTY_OBJECT || deferredName != null) {
       throw new IllegalStateException("Nesting problem.");
     }
-    pathNames[stackSize - 1] = name;
     deferredName = name;
+    pathNames[stackSize - 1] = name;
+    promoteValueToName = false;
     return this;
   }
 
   @Override public JsonWriter value(String value) throws IOException {
+    if (promoteValueToName) {
+      return name(value);
+    }
     add(value);
     pathIndices[stackSize - 1]++;
     return this;
@@ -130,6 +135,9 @@ final class ObjectJsonWriter extends JsonWriter {
   }
 
   @Override public JsonWriter value(long value) throws IOException {
+    if (promoteValueToName) {
+      return name(Long.toString(value));
+    }
     add(value);
     pathIndices[stackSize - 1]++;
     return this;
@@ -142,15 +150,14 @@ final class ObjectJsonWriter extends JsonWriter {
         throw new IllegalArgumentException("Numeric values must be finite, but was " + value);
       }
     }
+    if (promoteValueToName) {
+      return name(value.toString());
+    }
     add(value);
     pathIndices[stackSize - 1]++;
     return this;
   }
 
-  @Override void promoteNameToValue() throws IOException {
-    throw new UnsupportedOperationException();
-  }
-
   @Override public void close() throws IOException {
     int size = stackSize;
     if (size > 1 || size == 1 && scopes[size - 1] != NONEMPTY_DOCUMENT) {
diff --git a/moshi/src/test/java/com/squareup/moshi/MapJsonAdapterTest.java b/moshi/src/test/java/com/squareup/moshi/MapJsonAdapterTest.java
index 0fb1955..bb07498 100644
--- a/moshi/src/test/java/com/squareup/moshi/MapJsonAdapterTest.java
+++ b/moshi/src/test/java/com/squareup/moshi/MapJsonAdapterTest.java
@@ -125,6 +125,22 @@ public final class MapJsonAdapterTest {
         MapEntry.entry(5, true), MapEntry.entry(6, false), MapEntry.entry(7, null));
   }
 
+  @Test public void mapWithNonStringKeysToJsonObject() throws Exception {
+    Map<Integer, Boolean> map = new LinkedHashMap<>();
+    map.put(5, true);
+    map.put(6, false);
+    map.put(7, null);
+
+    Map<String, Boolean> jsonObject = new LinkedHashMap<>();
+    jsonObject.put("5", true);
+    jsonObject.put("6", false);
+    jsonObject.put("7", null);
+
+    JsonAdapter<Map<Integer, Boolean>> jsonAdapter = mapAdapter(Integer.class, Boolean.class);
+    assertThat(jsonAdapter.serializeNulls().toJsonObject(map)).isEqualTo(jsonObject);
+    assertThat(jsonAdapter.fromJsonObject(jsonObject)).isEqualTo(map);
+  }
+
   private <K, V> String toJson(Type keyType, Type valueType, Map<K, V> value) throws IOException {
     JsonAdapter<Map<K, V>> jsonAdapter = mapAdapter(keyType, valueType);
     Buffer buffer = new Buffer();
diff --git a/moshi/src/test/java/com/squareup/moshi/PromoteNameToValueTest.java b/moshi/src/test/java/com/squareup/moshi/PromoteNameToValueTest.java
index 284b095..c50005d 100644
--- a/moshi/src/test/java/com/squareup/moshi/PromoteNameToValueTest.java
+++ b/moshi/src/test/java/com/squareup/moshi/PromoteNameToValueTest.java
@@ -15,15 +15,27 @@
  */
 package com.squareup.moshi;
 
-import okio.Buffer;
+import java.util.List;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameter;
+import org.junit.runners.Parameterized.Parameters;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.fail;
 
+@RunWith(Parameterized.class)
 public final class PromoteNameToValueTest {
+  @Parameter public JsonCodecFactory factory;
+
+  @Parameters(name = "{0}")
+  public static List<Object[]> parameters() {
+    return JsonCodecFactory.factories();
+  }
+
   @Test public void readerStringValue() throws Exception {
-    JsonReader reader = newReader("{\"a\":1}");
+    JsonReader reader = factory.newReader("{\"a\":1}");
     reader.beginObject();
     reader.promoteNameToValue();
     assertThat(reader.getPath()).isEqualTo("$.a");
@@ -37,7 +49,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerIntegerValue() throws Exception {
-    JsonReader reader = newReader("{\"5\":1}");
+    JsonReader reader = factory.newReader("{\"5\":1}");
     reader.beginObject();
     reader.promoteNameToValue();
     assertThat(reader.getPath()).isEqualTo("$.5");
@@ -51,7 +63,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerDoubleValue() throws Exception {
-    JsonReader reader = newReader("{\"5.5\":1}");
+    JsonReader reader = factory.newReader("{\"5.5\":1}");
     reader.beginObject();
     reader.promoteNameToValue();
     assertThat(reader.getPath()).isEqualTo("$.5.5");
@@ -65,7 +77,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerBooleanValue() throws Exception {
-    JsonReader reader = newReader("{\"true\":1}");
+    JsonReader reader = factory.newReader("{\"true\":1}");
     reader.beginObject();
     reader.promoteNameToValue();
     assertThat(reader.getPath()).isEqualTo("$.true");
@@ -74,7 +86,9 @@ public final class PromoteNameToValueTest {
       reader.nextBoolean();
       fail();
     } catch (JsonDataException e) {
-      assertThat(e).hasMessage("Expected a boolean but was STRING at path $.true");
+      assertThat(e.getMessage()).isIn(
+          "Expected BOOLEAN but was true, a java.lang.String, at path $.true",
+          "Expected a boolean but was STRING at path $.true");
     }
     assertThat(reader.getPath()).isEqualTo("$.true");
     assertThat(reader.nextString()).isEqualTo("true");
@@ -85,7 +99,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerLongValue() throws Exception {
-    JsonReader reader = newReader("{\"5\":1}");
+    JsonReader reader = factory.newReader("{\"5\":1}");
     reader.beginObject();
     reader.promoteNameToValue();
     assertThat(reader.getPath()).isEqualTo("$.5");
@@ -99,7 +113,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerNullValue() throws Exception {
-    JsonReader reader = newReader("{\"null\":1}");
+    JsonReader reader = factory.newReader("{\"null\":1}");
     reader.beginObject();
     reader.promoteNameToValue();
     assertThat(reader.getPath()).isEqualTo("$.null");
@@ -108,7 +122,9 @@ public final class PromoteNameToValueTest {
       reader.nextNull();
       fail();
     } catch (JsonDataException e) {
-      assertThat(e).hasMessage("Expected null but was STRING at path $.null");
+      assertThat(e.getMessage()).isIn(
+          "Expected NULL but was null, a java.lang.String, at path $.null",
+          "Expected null but was STRING at path $.null");
     }
     assertThat(reader.nextString()).isEqualTo("null");
     assertThat(reader.getPath()).isEqualTo("$.null");
@@ -119,7 +135,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerMultipleValueObject() throws Exception {
-    JsonReader reader = newReader("{\"a\":1,\"b\":2}");
+    JsonReader reader = factory.newReader("{\"a\":1,\"b\":2}");
     reader.beginObject();
     assertThat(reader.nextName()).isEqualTo("a");
     assertThat(reader.nextInt()).isEqualTo(1);
@@ -135,7 +151,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerEmptyValueObject() throws Exception {
-    JsonReader reader = newReader("{}");
+    JsonReader reader = factory.newReader("{}");
     reader.beginObject();
     assertThat(reader.peek()).isEqualTo(JsonReader.Token.END_OBJECT);
     reader.promoteNameToValue();
@@ -145,7 +161,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerUnusedPromotionDoesntPersist() throws Exception {
-    JsonReader reader = newReader("[{},{\"a\":5}]");
+    JsonReader reader = factory.newReader("[{},{\"a\":5}]");
     reader.beginArray();
     reader.beginObject();
     reader.promoteNameToValue();
@@ -160,7 +176,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerUnquotedIntegerValue() throws Exception {
-    JsonReader reader = newReader("{5:1}");
+    JsonReader reader = factory.newReader("{5:1}");
     reader.setLenient(true);
     reader.beginObject();
     reader.promoteNameToValue();
@@ -170,7 +186,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerUnquotedLongValue() throws Exception {
-    JsonReader reader = newReader("{5:1}");
+    JsonReader reader = factory.newReader("{5:1}");
     reader.setLenient(true);
     reader.beginObject();
     reader.promoteNameToValue();
@@ -180,7 +196,7 @@ public final class PromoteNameToValueTest {
   }
 
   @Test public void readerUnquotedDoubleValue() throws Exception {
-    JsonReader reader = newReader("{5:1}");
+    JsonReader reader = factory.newReader("{5:1}");
     reader.setLenient(true);
     reader.beginObject();
     reader.promoteNameToValue();
@@ -189,57 +205,49 @@ public final class PromoteNameToValueTest {
     reader.endObject();
   }
 
-  private JsonReader newReader(String s) {
-    return JsonReader.of(new Buffer().writeUtf8(s));
-  }
-
   @Test public void writerStringValue() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     writer.value("a");
     assertThat(writer.getPath()).isEqualTo("$.a");
     writer.value(1);
     assertThat(writer.getPath()).isEqualTo("$.a");
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{\"a\":1}");
+    assertThat(factory.json()).isEqualTo("{\"a\":1}");
   }
 
   @Test public void writerIntegerValue() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     writer.value(5);
     assertThat(writer.getPath()).isEqualTo("$.5");
     writer.value(1);
     assertThat(writer.getPath()).isEqualTo("$.5");
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{\"5\":1}");
+    assertThat(factory.json()).isEqualTo("{\"5\":1}");
   }
 
   @Test public void writerDoubleValue() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     writer.value(5.5d);
     assertThat(writer.getPath()).isEqualTo("$.5.5");
     writer.value(1);
     assertThat(writer.getPath()).isEqualTo("$.5.5");
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{\"5.5\":1}");
+    assertThat(factory.json()).isEqualTo("{\"5.5\":1}");
   }
 
   @Test public void writerBooleanValue() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     try {
       writer.value(true);
       fail();
@@ -251,28 +259,26 @@ public final class PromoteNameToValueTest {
     writer.value(1);
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{\"true\":1}");
+    assertThat(factory.json()).isEqualTo("{\"true\":1}");
   }
 
   @Test public void writerLongValue() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     writer.value(5L);
     assertThat(writer.getPath()).isEqualTo("$.5");
     writer.value(1);
     assertThat(writer.getPath()).isEqualTo("$.5");
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{\"5\":1}");
+    assertThat(factory.json()).isEqualTo("{\"5\":1}");
   }
 
   @Test public void writerNullValue() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     try {
       writer.nullValue();
       fail();
@@ -285,42 +291,39 @@ public final class PromoteNameToValueTest {
     assertThat(writer.getPath()).isEqualTo("$.null");
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{\"null\":1}");
+    assertThat(factory.json()).isEqualTo("{\"null\":1}");
   }
 
   @Test public void writerMultipleValueObject() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
     writer.name("a");
     writer.value(1);
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     writer.value("b");
     assertThat(writer.getPath()).isEqualTo("$.b");
     writer.value(2);
     assertThat(writer.getPath()).isEqualTo("$.b");
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{\"a\":1,\"b\":2}");
+    assertThat(factory.json()).isEqualTo("{\"a\":1,\"b\":2}");
   }
 
   @Test public void writerEmptyValueObject() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     assertThat(writer.getPath()).isEqualTo("$.");
     writer.endObject();
     assertThat(writer.getPath()).isEqualTo("$");
-    assertThat(buffer.readUtf8()).isEqualTo("{}");
+    assertThat(factory.json()).isEqualTo("{}");
   }
 
   @Test public void writerUnusedPromotionDoesntPersist() throws Exception {
-    Buffer buffer = new Buffer();
-    JsonWriter writer = JsonWriter.of(buffer);
+    JsonWriter writer = factory.newWriter();
     writer.beginArray();
     writer.beginObject();
-    writer.promoteNameToValue();
+    writer.promoteValueToName();
     writer.endObject();
     writer.beginObject();
     try {