diff --git a/compiler/src/main/cpp/capnpc-java.c++ b/compiler/src/main/cpp/capnpc-java.c++
index fa404e0..a541cbb 100644
--- a/compiler/src/main/cpp/capnpc-java.c++
+++ b/compiler/src/main/cpp/capnpc-java.c++
@@ -1201,8 +1201,7 @@ private:
         spaces(indent), "      return ", fullName, ".STRUCT_SIZE;\n",
         spaces(indent), "    }\n",
         spaces(indent), "    public final Reader asReader(Builder builder) {\n",
-        spaces(indent), "      throw new Error();\n",
-//        spaces(indent), "      return new Reader(builder._builder.asReader());\n",
+        spaces(indent), "      return builder.asReader();\n",
         spaces(indent), "    }\n",
 
         spaces(indent), "  }\n",
diff --git a/runtime/src/main/java/org/capnproto/StructBuilder.java b/runtime/src/main/java/org/capnproto/StructBuilder.java
index 91d592f..efb64e2 100644
--- a/runtime/src/main/java/org/capnproto/StructBuilder.java
+++ b/runtime/src/main/java/org/capnproto/StructBuilder.java
@@ -19,17 +19,17 @@ public class StructBuilder {
         this.bit0Offset = bit0Offset;
     }
 
-    public final boolean _getBooleanField(int offset) {
+    protected final boolean _getBooleanField(int offset) {
         int bitOffset = (offset == 0 ? this.bit0Offset : offset);
         int position = this.data + (bitOffset / 8);
         return (this.segment.buffer.get(position) & (1 << (bitOffset % 8))) != 0;
     }
 
-    public final boolean getBooleanField(int offset, boolean mask) {
+    protected final boolean getBooleanField(int offset, boolean mask) {
         return this._getBooleanField(offset) ^ mask;
     }
 
-    public final void _setBooleanField(int offset, boolean value) {
+    protected final void _setBooleanField(int offset, boolean value) {
         int bitOffset = offset;
         if (offset == 0) { bitOffset = this.bit0Offset; }
         byte bitnum = (byte)(bitOffset % 8);
@@ -39,111 +39,111 @@ public class StructBuilder {
                                 (byte)((oldValue & (~(1 << bitnum))) | (( value ? 1 : 0) << bitnum)));
     }
 
-    public final void _setBooleanField(int offset, boolean value, boolean mask) {
+    protected final void _setBooleanField(int offset, boolean value, boolean mask) {
         this._setBooleanField(offset, value ^ mask);
     }
 
-    public final byte _getByteField(int offset) {
+    protected final byte _getByteField(int offset) {
         return this.segment.buffer.get(this.data + offset);
     }
 
-    public final byte _getByteField(int offset, byte mask) {
+    protected final byte _getByteField(int offset, byte mask) {
         return (byte)(this._getByteField(offset) ^ mask);
     }
 
-    public final void _setByteField(int offset, byte value) {
+    protected final void _setByteField(int offset, byte value) {
         this.segment.buffer.put(this.data + offset, value);
     }
 
-    public final void _setByteField(int offset, byte value, byte mask) {
+    protected final void _setByteField(int offset, byte value, byte mask) {
         this._setByteField(offset, (byte) (value ^ mask));
     }
 
-    public final short _getShortField(int offset) {
+    protected final short _getShortField(int offset) {
         return this.segment.buffer.getShort(this.data + offset * 2);
     }
 
-    public final short _getShortField(int offset, short mask) {
+    protected final short _getShortField(int offset, short mask) {
         return (short)(this._getShortField(offset) ^ mask);
     }
 
-    public final void _setShortField(int offset, short value) {
+    protected final void _setShortField(int offset, short value) {
         this.segment.buffer.putShort(this.data + offset * 2, value);
     }
 
-    public final void _setShortField(int offset, short value, short mask) {
+    protected final void _setShortField(int offset, short value, short mask) {
         this._setShortField(offset, (short)(value ^ mask));
     }
 
-    public final int _getIntField(int offset) {
+    protected final int _getIntField(int offset) {
         return this.segment.buffer.getInt(this.data + offset * 4);
     }
 
-    public final int _getIntField(int offset, int mask) {
+    protected final int _getIntField(int offset, int mask) {
         return this._getIntField(offset) ^ mask;
     }
 
-    public final void _setIntField(int offset, int value) {
+    protected final void _setIntField(int offset, int value) {
         this.segment.buffer.putInt(this.data + offset * 4, value);
     }
 
-    public final void _setIntField(int offset, int value, int mask) {
+    protected final void _setIntField(int offset, int value, int mask) {
         this._setIntField(offset, value ^ mask);
     }
 
-    public final long _getLongField(int offset) {
+    protected final long _getLongField(int offset) {
         return this.segment.buffer.getLong(this.data + offset * 8);
     }
 
-    public final long _getLongField(int offset, long mask) {
+    protected final long _getLongField(int offset, long mask) {
         return this._getLongField(offset) ^ mask;
     }
 
-    public final void _setLongField(int offset, long value) {
+    protected final void _setLongField(int offset, long value) {
         this.segment.buffer.putLong(this.data + offset * 8, value);
     }
 
-    public final void _setLongField(int offset, long value, long mask) {
+    protected final void _setLongField(int offset, long value, long mask) {
         this._setLongField(offset, value ^ mask);
     }
 
-    public final float _getFloatField(int offset) {
+    protected final float _getFloatField(int offset) {
         return this.segment.buffer.getFloat(this.data + offset * 4);
     }
 
-    public final float _getFloatField(int offset, int mask) {
+    protected final float _getFloatField(int offset, int mask) {
         return Float.intBitsToFloat(
             this.segment.buffer.getInt(this.data + offset * 4) ^ mask);
     }
 
-    public final void _setFloatField(int offset, float value) {
+    protected final void _setFloatField(int offset, float value) {
         this.segment.buffer.putFloat(this.data + offset * 4, value);
     }
 
-    public final void _setFloatField(int offset, float value, int mask) {
+    protected final void _setFloatField(int offset, float value, int mask) {
         this.segment.buffer.putInt(this.data + offset * 4,
                                    Float.floatToIntBits(value) ^ mask);
     }
 
-    public final double _getDoubleField(int offset) {
+    protected final double _getDoubleField(int offset) {
         return this.segment.buffer.getDouble(this.data + offset * 8);
     }
 
-    public final double _getDoubleField(int offset, long mask) {
+    protected final double _getDoubleField(int offset, long mask) {
         return Double.longBitsToDouble(
             this.segment.buffer.getLong(this.data + offset * 8) ^ mask);
     }
 
-    public final void _setDoubleField(int offset, double value) {
+    protected final void _setDoubleField(int offset, double value) {
         this.segment.buffer.putDouble(this.data + offset * 8, value);
     }
 
-    public final void _setDoubleField(int offset, double value, long mask) {
+    protected final void _setDoubleField(int offset, double value, long mask) {
         this.segment.buffer.putLong(this.data + offset * 8,
                                     Double.doubleToLongBits(value) ^ mask);
     }
 
-    public final PointerBuilder _getPointerField(int index) {
+    protected final PointerBuilder _getPointerField(int index) {
         return new PointerBuilder(this.segment, this.pointers + index);
     }
 
diff --git a/runtime/src/main/java/org/capnproto/StructReader.java b/runtime/src/main/java/org/capnproto/StructReader.java
index 1176dae..e7f2f1b 100644
--- a/runtime/src/main/java/org/capnproto/StructReader.java
+++ b/runtime/src/main/java/org/capnproto/StructReader.java
@@ -32,7 +32,7 @@ public class StructReader {
         this.nestingLimit = nestingLimit;
     }
 
-    public final boolean _getBooleanField(int offset) {
+    protected final boolean _getBooleanField(int offset) {
         // XXX should use unsigned operations
         if (offset < this.dataSize) {
             if (offset == 0) {
@@ -46,11 +46,11 @@ public class StructReader {
         }
     }
 
-    public final boolean _getBooleanField(int offset, boolean mask) {
+    protected final boolean _getBooleanField(int offset, boolean mask) {
         return this._getBooleanField(offset) ^ mask;
     }
 
-    public final byte _getByteField(int offset) {
+    protected final byte _getByteField(int offset) {
         if ((offset + 1) * 8 <= this.dataSize) {
             return this.segment.buffer.get(this.data + offset);
         } else {
@@ -58,11 +58,11 @@ public class StructReader {
         }
     }
 
-    public final byte _getByteField(int offset, byte mask) {
+    protected final byte _getByteField(int offset, byte mask) {
         return (byte)(this._getByteField(offset) ^ mask);
     }
 
-    public final short _getShortField(int offset) {
+    protected final short _getShortField(int offset) {
         if ((offset + 1) * 16 <= this.dataSize) {
             return this.segment.buffer.getShort(this.data + offset * 2);
         } else {
@@ -70,11 +70,11 @@ public class StructReader {
         }
     }
 
-    public final short _getShortField(int offset, short mask) {
+    protected final short _getShortField(int offset, short mask) {
         return (short)(this._getShortField(offset) ^ mask);
     }
 
-    public final int _getIntField(int offset) {
+    protected final int _getIntField(int offset) {
         if ((offset + 1) * 32 <= this.dataSize) {
             return this.segment.buffer.getInt(this.data + offset * 4);
         } else {
@@ -82,11 +82,11 @@ public class StructReader {
         }
     }
 
-    public final int _getIntField(int offset, int mask) {
+    protected final int _getIntField(int offset, int mask) {
         return this._getIntField(offset) ^ mask;
     }
 
-    public final long _getLongField(int offset) {
+    protected final long _getLongField(int offset) {
         if ((offset + 1) * 64 <= this.dataSize) {
             return this.segment.buffer.getLong(this.data + offset * 8);
         } else {
@@ -94,11 +94,11 @@ public class StructReader {
         }
     }
 
-    public final long _getLongField(int offset, long mask) {
+    protected final long _getLongField(int offset, long mask) {
         return this._getLongField(offset) ^ mask;
     }
 
-    public final float _getFloatField(int offset) {
+    protected final float _getFloatField(int offset) {
         if ((offset + 1) * 32 <= this.dataSize) {
             return this.segment.buffer.getFloat(this.data + offset * 4);
         } else {
@@ -106,7 +106,7 @@ public class StructReader {
         }
     }
 
-    public final float _getFloatField(int offset, int mask) {
+    protected final float _getFloatField(int offset, int mask) {
         if ((offset + 1) * 32 <= this.dataSize) {
             return Float.intBitsToFloat(this.segment.buffer.getInt(this.data + offset * 4) ^ mask);
         } else {
@@ -114,7 +114,7 @@ public class StructReader {
         }
     }
 
-    public final double _getDoubleField(int offset) {
+    protected final double _getDoubleField(int offset) {
         if ((offset + 1) * 64 <= this.dataSize) {
             return this.segment.buffer.getDouble(this.data + offset * 8);
         } else {
@@ -122,7 +122,7 @@ public class StructReader {
         }
     }
 
-    public final double _getDoubleField(int offset, long mask) {
+    protected final double _getDoubleField(int offset, long mask) {
         if ((offset + 1) * 64 <= this.dataSize) {
             return Double.longBitsToDouble(this.segment.buffer.getLong(this.data + offset * 8) ^ mask);
         } else {
@@ -130,7 +130,7 @@ public class StructReader {
         }
     }
 
-    public final PointerReader _getPointerField(int ptrIndex) {
+    protected final PointerReader _getPointerField(int ptrIndex) {
         if (ptrIndex < this.pointerCount) {
             return new PointerReader(this.segment,
                 this.pointers + ptrIndex,
diff --git a/runtime/src/test/scala/org/capnproto/LayoutTest.scala b/runtime/src/test/scala/org/capnproto/LayoutTest.scala
index 85a466a..a7f4150 100644
--- a/runtime/src/test/scala/org/capnproto/LayoutTest.scala
+++ b/runtime/src/test/scala/org/capnproto/LayoutTest.scala
@@ -17,8 +17,8 @@ class LayoutSuite extends FunSuite {
     val pointerReader = new PointerReader(arena.tryGetSegment(0), 0, 0x7fffffff);
     val reader = pointerReader.getStruct();
 
-    assert(reader.getLongField(0) === 0xefcdab8967452301L);
-    assert(reader.getLongField(1) === 0L);
+    assert(reader._getLongField(0) === 0xefcdab8967452301L);
+    assert(reader._getLongField(1) === 0L);
 
     assert(reader.getIntField(0) === 0x67452301);
     assert(reader.getIntField(1) === 0xefcdab89);