diff --git a/moshi/src/main/java/com/squareup/moshi/BufferedSourceJsonReader.java b/moshi/src/main/java/com/squareup/moshi/BufferedSourceJsonReader.java
index 8f7d5a9..327c06b 100644
--- a/moshi/src/main/java/com/squareup/moshi/BufferedSourceJsonReader.java
+++ b/moshi/src/main/java/com/squareup/moshi/BufferedSourceJsonReader.java
@@ -304,7 +304,7 @@ final class BufferedSourceJsonReader extends JsonReader {
           break;
         case '=':
           checkLenient();
-          if (fillBuffer(1) && buffer.getByte(0) == '>') {
+          if (source.request(1) && buffer.getByte(0) == '>') {
             buffer.readByte(); // Consume '>'.
           }
           break;
@@ -400,7 +400,7 @@ final class BufferedSourceJsonReader extends JsonReader {
     // Confirm that chars [1..length) match the keyword.
     int length = keyword.length();
     for (int i = 1; i < length; i++) {
-      if (!fillBuffer(i + 1)) {
+      if (!source.request(i + 1)) {
         return PEEKED_NONE;
       }
       c = buffer.getByte(i);
@@ -409,7 +409,7 @@ final class BufferedSourceJsonReader extends JsonReader {
       }
     }
 
-    if (fillBuffer(length + 1) && isLiteral(buffer.getByte(length))) {
+    if (source.request(length + 1) && isLiteral(buffer.getByte(length))) {
       return PEEKED_NONE; // Don't match trues, falsey or nullsoft!
     }
 
@@ -428,7 +428,7 @@ final class BufferedSourceJsonReader extends JsonReader {
 
     charactersOfNumber:
     for (; true; i++) {
-      if (!fillBuffer(i + 1)) {
+      if (!source.request(i + 1)) {
         break;
       }
 
@@ -880,15 +880,6 @@ final class BufferedSourceJsonReader extends JsonReader {
     stack[stackSize++] = newTop;
   }
 
-  /**
-   * Returns true once {@code limit - pos >= minimum}. If the data is
-   * exhausted before that many characters are available, this returns
-   * false.
-   */
-  private boolean fillBuffer(int minimum) throws IOException {
-    return source.request(minimum);
-  }
-
   /**
    * Returns the next character in the stream that is neither whitespace nor a
    * part of a comment. When this returns, the returned character is always at
@@ -905,7 +896,7 @@ final class BufferedSourceJsonReader extends JsonReader {
      * 'p' and 'l' after any (potentially indirect) call to the same method.
      */
     int p = 0;
-    while (fillBuffer(p + 1)) {
+    while (source.request(p + 1)) {
       int c = buffer.getByte(p++);
       if (c == '\n' || c == ' ' || c == '\r' || c == '\t') {
         continue;
@@ -913,7 +904,7 @@ final class BufferedSourceJsonReader extends JsonReader {
 
       buffer.skip(p - 1);
       if (c == '/') {
-        if (!fillBuffer(2)) {
+        if (!source.request(2)) {
           return c;
         }
 
@@ -981,7 +972,7 @@ final class BufferedSourceJsonReader extends JsonReader {
    */
   private boolean skipTo(String toFind) throws IOException {
     outer:
-    for (; fillBuffer(toFind.length());) {
+    for (; source.request(toFind.length());) {
       for (int c = 0; c < toFind.length(); c++) {
         if (buffer.getByte(c) != toFind.charAt(c)) {
           buffer.readByte();
@@ -1009,14 +1000,14 @@ final class BufferedSourceJsonReader extends JsonReader {
    * @throws IOException if any unicode escape sequences are malformed.
    */
   private char readEscapeCharacter() throws IOException {
-    if (!fillBuffer(1)) {
+    if (!source.request(1)) {
       throw syntaxError("Unterminated escape sequence");
     }
 
     byte escaped = buffer.readByte();
     switch (escaped) {
       case 'u':
-        if (!fillBuffer(4)) {
+        if (!source.request(4)) {
           throw new EOFException("Unterminated escape sequence at path " + getPath());
         }
         // Equivalent to Integer.parseInt(stringPool.get(buffer, pos, 4), 16);
diff --git a/moshi/src/main/java/com/squareup/moshi/ClassJsonAdapter.java b/moshi/src/main/java/com/squareup/moshi/ClassJsonAdapter.java
index 3af3031..7947e9f 100644
--- a/moshi/src/main/java/com/squareup/moshi/ClassJsonAdapter.java
+++ b/moshi/src/main/java/com/squareup/moshi/ClassJsonAdapter.java
@@ -21,6 +21,7 @@ import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Type;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
@@ -81,11 +82,11 @@ final class ClassJsonAdapter<T> extends JsonAdapter<T> {
 
         // Create the binding between field and JSON.
         field.setAccessible(true);
-        FieldBinding<Object> fieldBinding = new FieldBinding<>(field, adapter);
 
         // Store it using the field's name. If there was already a field with this name, fail!
         Json jsonAnnotation = field.getAnnotation(Json.class);
         String name = jsonAnnotation != null ? jsonAnnotation.name() : field.getName();
+        FieldBinding<Object> fieldBinding = new FieldBinding<>(name, field, adapter);
         FieldBinding<?> replaced = fieldBindings.put(name, fieldBinding);
         if (replaced != null) {
           throw new IllegalArgumentException("Conflicting fields:\n"
@@ -113,11 +114,13 @@ final class ClassJsonAdapter<T> extends JsonAdapter<T> {
   };
 
   private final ClassFactory<T> classFactory;
-  private final Map<String, FieldBinding<?>> jsonFields;
+  private final Map<String, FieldBinding<?>> fieldsMap;
+  private final FieldBinding<?>[] fieldsArray;
 
-  ClassJsonAdapter(ClassFactory<T> classFactory, Map<String, FieldBinding<?>> jsonFields) {
+  ClassJsonAdapter(ClassFactory<T> classFactory, Map<String, FieldBinding<?>> fieldsMap) {
     this.classFactory = classFactory;
-    this.jsonFields = jsonFields;
+    this.fieldsMap = new LinkedHashMap<>(fieldsMap);
+    this.fieldsArray = fieldsMap.values().toArray(new FieldBinding[fieldsMap.size()]);
   }
 
   @Override public T fromJson(JsonReader reader) throws IOException {
@@ -139,7 +142,7 @@ final class ClassJsonAdapter<T> extends JsonAdapter<T> {
       reader.beginObject();
       while (reader.hasNext()) {
         String name = reader.nextName();
-        FieldBinding<?> fieldBinding = jsonFields.get(name);
+        FieldBinding<?> fieldBinding = fieldsMap.get(name);
         if (fieldBinding != null) {
           fieldBinding.read(reader, result);
         } else {
@@ -156,9 +159,9 @@ final class ClassJsonAdapter<T> extends JsonAdapter<T> {
   @Override public void toJson(JsonWriter writer, T value) throws IOException {
     try {
       writer.beginObject();
-      for (Map.Entry<String, FieldBinding<?>> entry : jsonFields.entrySet()) {
-        writer.name(entry.getKey());
-        entry.getValue().write(writer, value);
+      for (FieldBinding<?> fieldBinding : fieldsArray) {
+        writer.name(fieldBinding.name);
+        fieldBinding.write(writer, value);
       }
       writer.endObject();
     } catch (IllegalAccessException e) {
@@ -171,10 +174,12 @@ final class ClassJsonAdapter<T> extends JsonAdapter<T> {
   }
 
   static class FieldBinding<T> {
-    private final Field field;
-    private final JsonAdapter<T> adapter;
+    final String name;
+    final Field field;
+    final JsonAdapter<T> adapter;
 
-    public FieldBinding(Field field, JsonAdapter<T> adapter) {
+    public FieldBinding(String name, Field field, JsonAdapter<T> adapter) {
+      this.name = name;
       this.field = field;
       this.adapter = adapter;
     }