diff --git a/runtime/src/main/java/org/capnproto/MessageReader.java b/runtime/src/main/java/org/capnproto/MessageReader.java
index cc6cbd5..3b1dad5 100644
--- a/runtime/src/main/java/org/capnproto/MessageReader.java
+++ b/runtime/src/main/java/org/capnproto/MessageReader.java
@@ -27,12 +27,9 @@ public final class MessageReader {
     final ReaderArena arena;
     final int nestingLimit;
 
-    final static long DEFAULT_TRAVERSAL_LIMIT_IN_WORDS = 8 * 1024 * 1024;
-    final static int DEFAULT_NESTING_LIMIT = 64;
-
-    public MessageReader(ByteBuffer[] segmentSlices, long traversalLimitInWords, int nestingLimit) {
-        this.nestingLimit = nestingLimit;
-        this.arena = new ReaderArena(segmentSlices, traversalLimitInWords);
+    public MessageReader(ByteBuffer[] segmentSlices, ReaderOptions options) {
+        this.nestingLimit = options.nestingLimit;
+        this.arena = new ReaderArena(segmentSlices, options.traversalLimitInWords);
     }
 
     public <T> T getRoot(FromPointerReader<T> factory) {
diff --git a/runtime/src/main/java/org/capnproto/ReaderOptions.java b/runtime/src/main/java/org/capnproto/ReaderOptions.java
new file mode 100644
index 0000000..fa22b40
--- /dev/null
+++ b/runtime/src/main/java/org/capnproto/ReaderOptions.java
@@ -0,0 +1,39 @@
+// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package org.capnproto;
+
+public final class ReaderOptions {
+    public final long traversalLimitInWords;
+    public final int nestingLimit;
+
+    public ReaderOptions(long traversalLimitInWords, int nestingLimit) {
+        this.traversalLimitInWords = traversalLimitInWords;
+        this.nestingLimit = nestingLimit;
+    }
+
+    final static long DEFAULT_TRAVERSAL_LIMIT_IN_WORDS = 8 * 1024 * 1024;
+    final static int DEFAULT_NESTING_LIMIT = 64;
+
+    public static final ReaderOptions DEFAULT_READER_OPTIONS =
+        new ReaderOptions(DEFAULT_TRAVERSAL_LIMIT_IN_WORDS, DEFAULT_NESTING_LIMIT);
+
+}
diff --git a/runtime/src/main/java/org/capnproto/Serialize.java b/runtime/src/main/java/org/capnproto/Serialize.java
index d9fe344..a84a69a 100644
--- a/runtime/src/main/java/org/capnproto/Serialize.java
+++ b/runtime/src/main/java/org/capnproto/Serialize.java
@@ -48,10 +48,10 @@ public final class Serialize {
     }
 
     public static MessageReader read(ReadableByteChannel bc) throws IOException {
-        return read(bc, MessageReader.DEFAULT_TRAVERSAL_LIMIT_IN_WORDS, MessageReader.DEFAULT_NESTING_LIMIT);
+        return read(bc, ReaderOptions.DEFAULT_READER_OPTIONS);
     }
 
-    public static MessageReader read(ReadableByteChannel bc, long traversalLimitInWords, int nestingLimit) throws IOException {
+    public static MessageReader read(ReadableByteChannel bc, ReaderOptions options) throws IOException {
         ByteBuffer firstWord = makeByteBuffer(Constants.BYTES_PER_WORD);
         fillBuffer(firstWord, bc);
 
@@ -81,8 +81,7 @@ public final class Serialize {
             }
         }
 
-        // TODO check that totalWords is reasonable
-        if (totalWords > traversalLimitInWords) {
+        if (totalWords > options.traversalLimitInWords) {
             throw new DecodeException("Message size exceeds traversal limit.");
         }
 
@@ -105,7 +104,7 @@ public final class Serialize {
             offset += moreSizes.get(ii - 1);
         }
 
-        return new MessageReader(segmentSlices, traversalLimitInWords, nestingLimit);
+        return new MessageReader(segmentSlices, options);
     }
 
     public static void write(WritableByteChannel outputChannel,
diff --git a/runtime/src/main/java/org/capnproto/SerializePacked.java b/runtime/src/main/java/org/capnproto/SerializePacked.java
index dcddc55..caf10dc 100644
--- a/runtime/src/main/java/org/capnproto/SerializePacked.java
+++ b/runtime/src/main/java/org/capnproto/SerializePacked.java
@@ -24,13 +24,22 @@ package org.capnproto;
 public final class SerializePacked {
 
     public static MessageReader read(BufferedInputStream input) throws java.io.IOException {
+        return read(input, ReaderOptions.DEFAULT_READER_OPTIONS);
+    }
+
+    public static MessageReader read(BufferedInputStream input, ReaderOptions options) throws java.io.IOException {
         PackedInputStream packedInput = new PackedInputStream(input);
-        return Serialize.read(packedInput);
+        return Serialize.read(packedInput, options);
     }
 
     public static MessageReader readUnbuffered(java.nio.channels.ReadableByteChannel input) throws java.io.IOException {
+        return readUnbuffered(input, ReaderOptions.DEFAULT_READER_OPTIONS);
+    }
+
+    public static MessageReader readUnbuffered(java.nio.channels.ReadableByteChannel input,
+                                               ReaderOptions options) throws java.io.IOException {
         PackedInputStream packedInput = new PackedInputStream(new BufferedInputStreamWrapper(input));
-        return Serialize.read(packedInput);
+        return Serialize.read(packedInput, options);
     }
 
     public static void write(BufferedOutputStream output,