diff --git a/bind/genjava.go b/bind/genjava.go
index 4099260..8632e66 100644
--- a/bind/genjava.go
+++ b/bind/genjava.go
@@ -538,12 +538,12 @@ var javaNameReplacer = strings.NewReplacer(
 )
 
 func (g *javaGen) javaPkgName(pkg *types.Package) string {
-	if g.javaPkg != "" {
-		return g.javaPkg
-	}
 	if pkg == nil {
 		return "go"
 	}
+	if g.javaPkg != "" {
+		return g.javaPkg
+	}
 	s := javaNameReplacer.Replace(pkg.Name())
 	// Look for Java keywords that are not Go keywords, and avoid using
 	// them as a package name.
diff --git a/bind/java/CustomPkgTest.java b/bind/java/CustomPkgTest.java
new file mode 100644
index 0000000..723389c
--- /dev/null
+++ b/bind/java/CustomPkgTest.java
@@ -0,0 +1,15 @@
+// Copyright 2016 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.
+
+package go;
+
+import android.test.InstrumentationTestCase;
+
+import org.golang.custompkg.Testpkg;
+
+public class CustomPkgTest extends InstrumentationTestCase {
+  public void testHi() {
+    Testpkg.Hi();
+  }
+}
diff --git a/bind/java/seq_test.go b/bind/java/seq_test.go
index 5535fcb..254e0bf 100644
--- a/bind/java/seq_test.go
+++ b/bind/java/seq_test.go
@@ -16,15 +16,18 @@ import (
 	"time"
 )
 
-// TestJavaSeqTest runs java test SeqTest.java.
-// This requires the gradle command in PATH and
-// the Android SDK whose path is available through ANDROID_HOME environment variable.
+func TestCustomPkg(t *testing.T) {
+	runTest(t, []string{
+		"golang.org/x/mobile/bind/testpkg",
+	}, "org.golang.custompkg", "CustomPkgTest")
+}
+
 func TestJavaSeqTest(t *testing.T) {
 	runTest(t, []string{
 		"golang.org/x/mobile/bind/testpkg",
 		"golang.org/x/mobile/bind/testpkg/secondpkg",
 		"golang.org/x/mobile/bind/testpkg/simplepkg",
-	}, "SeqTest")
+	}, "", "SeqTest")
 }
 
 // TestJavaSeqBench runs java test SeqBench.java, with the same
@@ -38,10 +41,15 @@ func TestJavaSeqTest(t *testing.T) {
 //
 // while running the benchmark to see the results.
 func TestJavaSeqBench(t *testing.T) {
-	runTest(t, []string{"golang.org/x/mobile/bind/benchmark"}, "SeqBench")
+	runTest(t, []string{"golang.org/x/mobile/bind/benchmark"}, "", "SeqBench")
 }
 
-func runTest(t *testing.T, pkgNames []string, javaCls string) {
+// runTest runs the Android java test class specified with javaCls. If javaPkg is
+// set, it is passed with the -javapkg flag to gomobile. The pkgNames lists the Go
+// packages to bind for the test.
+// This requires the gradle command in PATH and
+// the Android SDK whose path is available through ANDROID_HOME environment variable.
+func runTest(t *testing.T, pkgNames []string, javaPkg, javaCls string) {
 	if _, err := run("which gradle"); err != nil {
 		t.Skip("command gradle not found, skipping")
 	}
@@ -84,7 +92,12 @@ func runTest(t *testing.T, pkgNames []string, javaCls string) {
 		}
 	}
 
-	buf, err := run("gomobile bind -o pkg.aar " + strings.Join(pkgNames, " "))
+	cmd := []string{"gomobile", "bind", "-o", "pkg.aar"}
+	if javaPkg != "" {
+		cmd = append(cmd, "-javapkg", javaPkg)
+	}
+	cmd = append(cmd, pkgNames...)
+	buf, err := run(strings.Join(cmd, " "))
 	if err != nil {
 		t.Logf("%s", buf)
 		t.Fatalf("failed to run gomobile bind: %v", err)