diff --git a/app/GoNativeActivity.java b/app/GoNativeActivity.java
new file mode 100644
index 0000000..4a1234b
--- /dev/null
+++ b/app/GoNativeActivity.java
@@ -0,0 +1,51 @@
+package org.golang.app;
+
+import android.app.Activity;
+import android.app.NativeActivity;
+import android.content.Context;
+import android.content.pm.ActivityInfo;
+import android.content.pm.PackageManager;
+import android.os.Bundle;
+import android.util.Log;
+
+public class GoNativeActivity extends NativeActivity {
+	private static GoNativeActivity goNativeActivity;
+
+	public GoNativeActivity() {
+		super();
+		goNativeActivity = this;
+	}
+
+	String getTmpdir() {
+		return getCacheDir().getAbsolutePath();
+	}
+
+	private void load() {
+		// Interestingly, NativeActivity uses a different method
+		// to find native code to execute, avoiding
+		// System.loadLibrary. The result is Java methods
+		// implemented in C with JNIEXPORT (and JNI_OnLoad) are not
+		// available unless an explicit call to System.loadLibrary
+		// is done. So we do it here, borrowing the name of the
+		// library from the same AndroidManifest.xml metadata used
+		// by NativeActivity.
+		try {
+			ActivityInfo ai = getPackageManager().getActivityInfo(
+					getIntent().getComponent(), PackageManager.GET_META_DATA);
+			if (ai.metaData == null) {
+				Log.e("Go", "loadLibrary: no manifest metadata found");
+				return;
+			}
+			String libName = ai.metaData.getString("android.app.lib_name");
+			System.loadLibrary(libName);
+		} catch (Exception e) {
+			Log.e("Go", "loadLibrary failed", e);
+		}
+	}
+
+	@Override
+	public void onCreate(Bundle savedInstanceState) {
+		load();
+		super.onCreate(savedInstanceState);
+	}
+}
diff --git a/app/android.c b/app/android.c
index 6f7b6e2..cd4dfd0 100644
--- a/app/android.c
+++ b/app/android.c
@@ -21,6 +21,7 @@
 static jclass find_class(JNIEnv *env, const char *class_name) {
 	jclass clazz = (*env)->FindClass(env, class_name);
 	if (clazz == NULL) {
+		(*env)->ExceptionClear(env);
 		LOG_FATAL("cannot find %s", class_name);
 		return NULL;
 	}
@@ -30,6 +31,7 @@ static jclass find_class(JNIEnv *env, const char *class_name) {
 static jmethodID find_method(JNIEnv *env, jclass clazz, const char *name, const char *sig) {
 	jmethodID m = (*env)->GetMethodID(env, clazz, name, sig);
 	if (m == 0) {
+		(*env)->ExceptionClear(env);
 		LOG_FATAL("cannot find method %s %s", name, sig);
 		return 0;
 	}
@@ -42,92 +44,41 @@ jint JNI_OnLoad(JavaVM* vm, void* reserved) {
 		return -1;
 	}
 
+	// Load classes here, which uses the correct ClassLoader.
 	current_vm = vm;
 	current_ctx = NULL;
+	current_ctx_clazz = find_class(env, "org/golang/app/GoNativeActivity");
+	current_ctx_clazz = (jclass)(*env)->NewGlobalRef(env, current_ctx_clazz);
 
 	return JNI_VERSION_1_6;
 }
 
-static void init_from_context() {
-	if (current_ctx == NULL) {
-		return;
+// Entry point from our subclassed NativeActivity.
+//
+// By here, the Go runtime has been initialized (as we are running in
+// -buildmode=c-shared) but main.main hasn't been called yet.
+void ANativeActivity_onCreate(ANativeActivity *activity, void* savedState, size_t savedStateSize) {
+	JNIEnv* env = activity->env;
+
+	// Note that activity->clazz is mis-named.
+	current_vm = activity->vm;
+	current_ctx = (*env)->NewGlobalRef(env, activity->clazz);
+
+	// Set TMPDIR.
+	jmethodID gettmpdir = find_method(env, current_ctx_clazz, "getTmpdir", "()Ljava/lang/String;");
+	jstring jpath = (jstring)(*env)->CallObjectMethod(env, current_ctx, gettmpdir, NULL);
+	const char* tmpdir = (*env)->GetStringUTFChars(env, jpath, NULL);
+	if (setenv("TMPDIR", tmpdir, 1) != 0) {
+		LOG_INFO("setenv(\"TMPDIR\", \"%s\", 1) failed: %d", tmpdir, errno);
 	}
+	(*env)->ReleaseStringUTFChars(env, jpath, tmpdir);
 
-	int attached = 0;
-	JNIEnv* env;
-	switch ((*current_vm)->GetEnv(current_vm, (void**)&env, JNI_VERSION_1_6)) {
-	case JNI_OK:
-		break;
-	case JNI_EDETACHED:
-		if ((*current_vm)->AttachCurrentThread(current_vm, &env, 0) != 0) {
-			LOG_FATAL("cannot attach JVM");
-		}
-		attached = 1;
-		break;
-	case JNI_EVERSION:
-		LOG_FATAL("bad JNI version");
-	}
-
-	// String path = context.getCacheDir().getAbsolutePath();
-	jclass context_clazz = find_class(env, "android/content/Context");
-	jmethodID getcachedir = find_method(env, context_clazz, "getCacheDir", "()Ljava/io/File;");
-	jobject file = (*env)->CallObjectMethod(env, current_ctx, getcachedir, NULL);
-	jclass file_clazz = find_class(env, "java/io/File");
-	jmethodID getabsolutepath = find_method(env, file_clazz, "getAbsolutePath", "()Ljava/lang/String;");
-	jstring jpath = (jstring)(*env)->CallObjectMethod(env, file, getabsolutepath, NULL);
-	const char* path = (*env)->GetStringUTFChars(env, jpath, NULL);
-	if (setenv("TMPDIR", path, 1) != 0) {
-		LOG_INFO("setenv(\"TMPDIR\", \"%s\", 1) failed: %d", path, errno);
-	}
-	(*env)->ReleaseStringUTFChars(env, jpath, path);
-
-	if (attached) {
-		(*current_vm)->DetachCurrentThread(current_vm);
-	}
-}
-
-// has_prefix_key returns 1 if s starts with prefix.
-static int has_prefix(const char *s, const char* prefix) {
-	while (*prefix) {
-		if (*prefix++ != *s++)
-			return 0;
-	}
-	return 1;
-}
-
-// getenv_raw searches environ for name prefix and returns the string pair.
-// For example, getenv_raw("PATH=") returns "PATH=/bin".
-// If no entry is found, the name prefix is returned. For example "PATH=".
-static const char* getenv_raw(const char *name) {
-	extern char** environ;
-	char** env = environ;
-
-	for (env = environ; *env; env++) {
-		if (has_prefix(*env, name)) {
-			return *env;
-		}
-	}
-	return name;
-}
-
-static void* call_main_and_wait() {
-	init_from_context();
+	// Call the Go main.main.
 	uintptr_t mainPC = (uintptr_t)dlsym(RTLD_DEFAULT, "main.main");
 	if (!mainPC) {
 		LOG_FATAL("missing main.main");
 	}
 	callMain(mainPC);
-}
-
-// Entry point from NativeActivity.
-//
-// By here, the Go runtime has been initialized (as we are running in
-// -buildmode=c-shared) but main.main hasn't been called yet.
-void ANativeActivity_onCreate(ANativeActivity *activity, void* savedState, size_t savedStateSize) {
-	// Note that activity->clazz is mis-named.
-	current_vm = activity->vm;
-	current_ctx = (*activity->env)->NewGlobalRef(activity->env, activity->clazz);
-	call_main_and_wait();
 
 	// These functions match the methods on Activity, described at
 	// http://developer.android.com/reference/android/app/Activity.html
diff --git a/app/android.go b/app/android.go
index 6290c88..8e18c49 100644
--- a/app/android.go
+++ b/app/android.go
@@ -45,6 +45,8 @@ JavaVM* current_vm;
 // current_ctx is Android's android.context.Context. May be NULL.
 jobject current_ctx;
 
+jclass current_ctx_clazz;
+
 jclass app_find_class(JNIEnv* env, const char* name);
 */
 import "C"
diff --git a/cmd/gomobile/build.go b/cmd/gomobile/build.go
index f4a2401..ba0ffcb 100644
--- a/cmd/gomobile/build.go
+++ b/cmd/gomobile/build.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:generate go run gendex.go -o dex.go
+
 package main
 
 import (
diff --git a/cmd/gomobile/build_androidapp.go b/cmd/gomobile/build_androidapp.go
index e366abe..7fcbe15 100644
--- a/cmd/gomobile/build_androidapp.go
+++ b/cmd/gomobile/build_androidapp.go
@@ -7,12 +7,14 @@ package main
 import (
 	"bytes"
 	"crypto/x509"
+	"encoding/base64"
 	"encoding/pem"
 	"errors"
 	"fmt"
 	"go/build"
 	"io"
 	"io/ioutil"
+	"log"
 	"os"
 	"path"
 	"path/filepath"
@@ -109,6 +111,18 @@ func goAndroidBuild(pkg *build.Package) error {
 		return err
 	}
 
+	w, err = apkwcreate("classes.dex")
+	if err != nil {
+		return err
+	}
+	dexData, err := base64.StdEncoding.DecodeString(dexStr)
+	if err != nil {
+		log.Fatal("internal error bad dexStr: %v", err)
+	}
+	if _, err := w.Write(dexData); err != nil {
+		return err
+	}
+
 	w, err = apkwcreate("lib/armeabi/lib" + libName + ".so")
 	if err != nil {
 		return err
diff --git a/cmd/gomobile/dex.go b/cmd/gomobile/dex.go
new file mode 100644
index 0000000..b1a191a
--- /dev/null
+++ b/cmd/gomobile/dex.go
@@ -0,0 +1,44 @@
+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// File is automatically generated by gendex.go. DO NOT EDIT.
+
+package main
+
+var dexStr = `ZGV4CjAzNQBgMPcbh5xnMiJMhJmv7LSwWLsd8n8QqVIUBwAAcAAAAHhWNBIAAAAAAAAAAH` +
+	`QGAAApAAAAcAAAAA8AAAAUAQAADAAAAFABAAACAAAA4AEAABAAAADwAQAAAQAAAHACAACE` +
+	`BAAAkAIAAJ4DAACmAwAAqgMAAMEDAADEAwAAyQMAAM8DAADSAwAA1gMAANsDAAD5AwAAGg` +
+	`QAADQEAABXBAAAfAQAAJEEAAClBAAAtQQAAMwEAADgBAAA9AQAAAsFAAAuBQAAMQUAADUF` +
+	`AABLBQAATgUAAF8FAABwBQAAfQUAAIsFAACWBQAAqQUAALQFAAC/BQAA0QUAANcFAADkBQ` +
+	`AA+AUAACEGAAArBgAAAwAAAAkAAAAKAAAACwAAAAwAAAANAAAADgAAAA8AAAAQAAAAEQAA` +
+	`ABIAAAATAAAAFAAAABUAAAAWAAAABAAAAAAAAAB0AwAABQAAAAAAAAB8AwAABgAAAAIAAA` +
+	`AAAAAABgAAAAMAAAAAAAAACAAAAAQAAACIAwAABgAAAAUAAAAAAAAABgAAAAgAAAAAAAAA` +
+	`BgAAAAoAAAAAAAAABwAAAAoAAACQAwAAFgAAAA4AAAAAAAAAFwAAAA4AAACYAwAAFwAAAA` +
+	`4AAACQAwAABAAGACcAAAANAA0AIgAAAAEACQAAAAAAAQAKACgAAAADAAIAHQAAAAUABAAb` +
+	`AAAABgAIACAAAAAHAAAAGQAAAAcAAQAZAAAACAAHABoAAAALAAsAJAAAAA0ACQAAAAAADQ` +
+	`AGABwAAAANAAMAHgAAAA0ABQAfAAAADQAHACEAAAANAAkAIwAAAA0ACgAoAAAADQAAAAEA` +
+	`AAABAAAAAAAAAAIAAAAAAAAAWQYAAAAAAAABAAEAAQAAADUGAAAGAAAAcBAAAAAAaQABAA` +
+	`4ABAABAAMAAQA8BgAAMwAAAG4QDAADAAwAbhALAAMADAFuEAIAAQAMARMCgABuMAMAEAIM` +
+	`AFQBAAA5AQoAGgABABoBJgBxIAUAEAAOAFQAAAAaARgAbiAEABAADABxEAgAAAAo9A0AGg` +
+	`EBABoCJQBxMAYAIQAo6wAAAAAAACkAAQABAQkqAgABAAEAAABMBgAACQAAAG4QCgABAAwA` +
+	`bhAHAAAADAARAAAAAgACAAIAAABRBgAABwAAAHAQDgAAAG8gAQAQAA4AAAACAAAACgAKAA` +
+	`MAAAAKAAoADAAAAAIAAAACAAAAAQAAAAoAAAABAAAABgAGPGluaXQ+AAJHbwAVR29OYXRp` +
+	`dmVBY3Rpdml0eS5qYXZhAAFJAANJTEwABElMTEwAAUwAAkxMAANMTEkAHExhbmRyb2lkL2` +
+	`FwcC9OYXRpdmVBY3Rpdml0eTsAH0xhbmRyb2lkL2NvbnRlbnQvQ29tcG9uZW50TmFtZTsA` +
+	`GExhbmRyb2lkL2NvbnRlbnQvSW50ZW50OwAhTGFuZHJvaWQvY29udGVudC9wbS9BY3Rpdm` +
+	`l0eUluZm87ACNMYW5kcm9pZC9jb250ZW50L3BtL1BhY2thZ2VNYW5hZ2VyOwATTGFuZHJv` +
+	`aWQvb3MvQnVuZGxlOwASTGFuZHJvaWQvdXRpbC9Mb2c7AA5MamF2YS9pby9GaWxlOwAVTG` +
+	`phdmEvbGFuZy9FeGNlcHRpb247ABJMamF2YS9sYW5nL1N0cmluZzsAEkxqYXZhL2xhbmcv` +
+	`U3lzdGVtOwAVTGphdmEvbGFuZy9UaHJvd2FibGU7ACFMb3JnL2dvbGFuZy9hcHAvR29OYX` +
+	`RpdmVBY3Rpdml0eTsAAVYAAlZMABRhbmRyb2lkLmFwcC5saWJfbmFtZQABZQAPZ2V0QWJz` +
+	`b2x1dGVQYXRoAA9nZXRBY3Rpdml0eUluZm8AC2dldENhY2hlRGlyAAxnZXRDb21wb25lbn` +
+	`QACWdldEludGVudAARZ2V0UGFja2FnZU1hbmFnZXIACWdldFN0cmluZwAJZ2V0VG1wZGly` +
+	`ABBnb05hdGl2ZUFjdGl2aXR5AARsb2FkAAtsb2FkTGlicmFyeQASbG9hZExpYnJhcnkgZm` +
+	`FpbGVkACdsb2FkTGlicmFyeTogbm8gbWFuaWZlc3QgbWV0YWRhdGEgZm91bmQACG1ldGFE` +
+	`YXRhAAhvbkNyZWF0ZQAPAAcOPC0AIQAHDgESEEt/Ansdh0seABQABw4AMAEABw48PAABAA` +
+	`ICAQoJgYAEkAUFAqwFDQCwBgIB1AYAAAANAAAAAAAAAAEAAAAAAAAAAQAAACkAAABwAAAA` +
+	`AgAAAA8AAAAUAQAAAwAAAAwAAABQAQAABAAAAAIAAADgAQAABQAAABAAAADwAQAABgAAAA` +
+	`EAAABwAgAAASAAAAQAAACQAgAAARAAAAUAAAB0AwAAAiAAACkAAACeAwAAAyAAAAQAAAA1` +
+	`BgAAACAAAAEAAABZBgAAABAAAAEAAAB0BgAA` +
+	``
diff --git a/cmd/gomobile/gendex.go b/cmd/gomobile/gendex.go
new file mode 100644
index 0000000..eb90d40
--- /dev/null
+++ b/cmd/gomobile/gendex.go
@@ -0,0 +1,157 @@
+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+// Gendex generates a dex file used by Go apps created with gomobile.
+//
+// The dex is a thin extension of NativeActivity, providing access to
+// a few platform features (not the SDK UI) not easily accessible from
+// NDK headers. Long term these could be made part of the standard NDK,
+// however that would limit gomobile to working with newer versions of
+// the Android OS, so we do this while we wait.
+//
+// Requires ANDROID_HOME be set to the path of the Android SDK, and
+// javac must be on the PATH.
+package main
+
+import (
+	"bytes"
+	"encoding/base64"
+	"errors"
+	"flag"
+	"fmt"
+	"go/format"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+var outfile = flag.String("o", "", "result will be written file")
+
+var tmpdir string
+
+func main() {
+	flag.Parse()
+
+	var err error
+	tmpdir, err = ioutil.TempDir("", "gendex-")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = gendex()
+	os.RemoveAll(tmpdir)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func gendex() error {
+	androidHome := os.Getenv("ANDROID_HOME")
+	if androidHome == "" {
+		return errors.New("ANDROID_HOME not set")
+	}
+	if err := os.MkdirAll(tmpdir+"/work/org/golang/app", 0775); err != nil {
+		return err
+	}
+	javaFiles, err := filepath.Glob("../../app/*.java")
+	if err != nil {
+		return err
+	}
+	if len(javaFiles) == 0 {
+		return errors.New("could not find ../../app/*.java files")
+	}
+	platform, err := findLast(androidHome + "/platforms")
+	if err != nil {
+		return err
+	}
+	cmd := exec.Command(
+		"javac",
+		"-source", "1.7",
+		"-target", "1.7",
+		"-bootclasspath", platform+"/android.jar",
+		"-d", tmpdir+"/work",
+	)
+	cmd.Args = append(cmd.Args, javaFiles...)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		fmt.Println(cmd.Args)
+		os.Stderr.Write(out)
+		return err
+	}
+	buildTools, err := findLast(androidHome + "/build-tools")
+	if err != nil {
+		return err
+	}
+	cmd = exec.Command(
+		buildTools+"/dx",
+		"--dex",
+		"--output="+tmpdir+"/classes.dex",
+		tmpdir+"/work",
+	)
+	if out, err := cmd.CombinedOutput(); err != nil {
+		os.Stderr.Write(out)
+		return err
+	}
+	src, err := ioutil.ReadFile(tmpdir + "/classes.dex")
+	if err != nil {
+		return err
+	}
+	data := base64.StdEncoding.EncodeToString(src)
+
+	buf := new(bytes.Buffer)
+	fmt.Fprint(buf, header)
+
+	var piece string
+	for len(data) > 0 {
+		l := 70
+		if l > len(data) {
+			l = len(data)
+		}
+		piece, data = data[:l], data[l:]
+		fmt.Fprintf(buf, "\t`%s` + \n", piece)
+	}
+	fmt.Fprintf(buf, "\t``")
+	out, err := format.Source(buf.Bytes())
+	if err != nil {
+		buf.WriteTo(os.Stderr)
+		return err
+	}
+
+	w, err := os.Create(*outfile)
+	if err != nil {
+		return err
+	}
+	if _, err := w.Write(out); err != nil {
+		return err
+	}
+	if err := w.Close(); err != nil {
+		return err
+	}
+	return nil
+}
+
+func findLast(path string) (string, error) {
+	dir, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	children, err := dir.Readdirnames(-1)
+	if err != nil {
+		return "", err
+	}
+	return path + "/" + children[len(children)-1], nil
+}
+
+var header = `// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// File is automatically generated by gendex.go. DO NOT EDIT.
+
+package main
+
+var dexStr = `
diff --git a/cmd/gomobile/manifest.go b/cmd/gomobile/manifest.go
index 04384e2..5ab308b 100644
--- a/cmd/gomobile/manifest.go
+++ b/cmd/gomobile/manifest.go
@@ -62,8 +62,8 @@ var manifestTmpl = template.Must(template.New("manifest").Parse(`
 	android:versionName="1.0">
 
 	<uses-sdk android:minSdkVersion="9" />
-	<application android:label="{{.Name}}" android:hasCode="false" android:debuggable="true">
-	<activity android:name="android.app.NativeActivity"
+	<application android:label="{{.Name}}" android:debuggable="true">
+	<activity android:name="org.golang.app.GoNativeActivity"
 		android:label="{{.Name}}"
 		android:configChanges="orientation|keyboardHidden">
 		<meta-data android:name="android.app.lib_name" android:value="{{.LibName}}" />
diff --git a/cmd/gomobile/writer.go b/cmd/gomobile/writer.go
index 3da75c8..6224f27 100644
--- a/cmd/gomobile/writer.go
+++ b/cmd/gomobile/writer.go
@@ -149,8 +149,20 @@ func (w *Writer) Close() error {
 		return fmt.Errorf("apk: %v", err)
 	}
 
+	hasDex := false
+	for _, entry := range w.manifest {
+		if entry.name == "classes.dex" {
+			hasDex = true
+			break
+		}
+	}
+
 	manifest := new(bytes.Buffer)
-	fmt.Fprint(manifest, manifestHeader)
+	if hasDex {
+		fmt.Fprint(manifest, manifestDexHeader)
+	} else {
+		fmt.Fprint(manifest, manifestHeader)
+	}
 	certBody := new(bytes.Buffer)
 
 	for _, entry := range w.manifest {
@@ -206,6 +218,12 @@ Created-By: 1.0 (Go)
 
 `
 
+const manifestDexHeader = `Manifest-Version: 1.0
+Dex-Location: classes.dex
+Created-By: 1.0 (Go)
+
+`
+
 const certHeader = `Signature-Version: 1.0
 Created-By: 1.0 (Go)
 `