diff --git a/cmd/gobind/main.go b/cmd/gobind/main.go
index 73552c5..c1f9490 100644
--- a/cmd/gobind/main.go
+++ b/cmd/gobind/main.go
@@ -51,8 +51,7 @@
 	} else {
 		langs = []string{"go", "java", "objc"}
 	}
-	oldCtx := build.Default
-	ctx := &build.Default
+	ctx := build.Default
 	if *tags != "" {
 		ctx.BuildTags = append(ctx.BuildTags, strings.Split(*tags, ",")...)
 	}
@@ -130,19 +129,14 @@
 		}
 	}
 
-	// Make sure the export data for any imported packages are up to date.
-	cmd := exec.Command("go", "install", "-tags", strings.Join(ctx.BuildTags, " "))
-	cmd.Args = append(cmd.Args, flag.Args()...)
-	cmd.Env = append(os.Environ(), "GOPATH="+ctx.GOPATH)
-	cmd.Env = append(cmd.Env, "GOROOT="+ctx.GOROOT)
-	if out, err := cmd.CombinedOutput(); err != nil {
-		fmt.Fprintf(os.Stderr, "%s", out)
-		exitStatus = 1
-		return
-	}
-
 	typePkgs := make([]*types.Package, len(allPkg))
-	imp := importer.Default()
+	// The "source" go/importer package implicitly uses build.Default.
+	oldCtx := build.Default
+	build.Default = ctx
+	defer func() {
+		build.Default = oldCtx
+	}()
+	imp := importer.For("source", nil)
 	for i, pkg := range allPkg {
 		var err error
 		typePkgs[i], err = imp.Import(pkg.ImportPath)
@@ -151,7 +145,6 @@
 			return
 		}
 	}
-	build.Default = oldCtx
 	for _, l := range langs {
 		for _, pkg := range typePkgs {
 			genPkg(l, pkg, typePkgs, classes, otypes)
diff --git a/cmd/gomobile/bind.go b/cmd/gomobile/bind.go
index 0d22d7d..248db89 100644
--- a/cmd/gomobile/bind.go
+++ b/cmd/gomobile/bind.go
@@ -97,6 +97,10 @@
 		return errors.New("no Android NDK path is set. Please run gomobile init with the ndk-bundle installed through the Android SDK manager or with the -ndk flag set.")
 	}
 
+	if ctx.GOOS == "darwin" {
+		ctx.BuildTags = append(ctx.BuildTags, "ios")
+	}
+
 	var gobind string
 	if !buildN {
 		gobind, err = exec.LookPath("gobind")
diff --git a/cmd/gomobile/bind_androidapp.go b/cmd/gomobile/bind_androidapp.go
index 145df64..2f65333 100644
--- a/cmd/gomobile/bind_androidapp.go
+++ b/cmd/gomobile/bind_androidapp.go
@@ -33,6 +33,7 @@
 		"-lang=go,java",
 		"-outdir="+tmpdir,
 	)
+	cmd.Env = append(cmd.Env, "GOOS=android")
 	if len(ctx.BuildTags) > 0 {
 		cmd.Args = append(cmd.Args, "-tags="+strings.Join(ctx.BuildTags, ","))
 	}
diff --git a/cmd/gomobile/bind_iosapp.go b/cmd/gomobile/bind_iosapp.go
index f8c4fdf..97fc670 100644
--- a/cmd/gomobile/bind_iosapp.go
+++ b/cmd/gomobile/bind_iosapp.go
@@ -21,6 +21,7 @@
 		"-lang=go,objc",
 		"-outdir="+tmpdir,
 	)
+	cmd.Env = append(cmd.Env, "GOOS=darwin")
 	if len(ctx.BuildTags) > 0 {
 		cmd.Args = append(cmd.Args, "-tags="+strings.Join(ctx.BuildTags, ","))
 	}
@@ -34,8 +35,6 @@
 		return err
 	}
 
-	ctx.BuildTags = append(ctx.BuildTags, "ios")
-
 	srcDir := filepath.Join(tmpdir, "src", "gobind")
 	gopath := fmt.Sprintf("GOPATH=%s%c%s", tmpdir, filepath.ListSeparator, goEnv("GOPATH"))
 
diff --git a/cmd/gomobile/bind_test.go b/cmd/gomobile/bind_test.go
index 1825666..62adf38 100644
--- a/cmd/gomobile/bind_test.go
+++ b/cmd/gomobile/bind_test.go
@@ -175,7 +175,7 @@
 
 var bindAndroidTmpl = template.Must(template.New("output").Parse(`GOMOBILE={{.GOPATH}}/pkg/gomobile
 WORK=$WORK
-gobind -lang=go,java -outdir=$WORK{{if .JavaPkg}} -javapkg={{.JavaPkg}}{{end}} golang.org/x/mobile/asset
+GOOS=android gobind -lang=go,java -outdir=$WORK{{if .JavaPkg}} -javapkg={{.JavaPkg}}{{end}} golang.org/x/mobile/asset
 GOOS=android GOARCH=arm CC=$GOMOBILE/ndk-toolchains/arm/bin/arm-linux-androideabi-clang CXX=$GOMOBILE/ndk-toolchains/arm/bin/arm-linux-androideabi-clang++ CGO_ENABLED=1 GOARM=7 GOPATH=$WORK:$GOPATH go build -x -buildmode=c-shared -o=$WORK/android/src/main/jniLibs/armeabi-v7a/libgojni.so gobind
 PWD=$WORK/java javac -d $WORK/javac-output -source 1.7 -target 1.7 -bootclasspath {{.AndroidPlatform}}/android.jar *.java
 jar c -C $WORK/javac-output .
@@ -183,7 +183,7 @@
 
 var bindIOSTmpl = template.Must(template.New("output").Parse(`GOMOBILE={{.GOPATH}}/pkg/gomobile
 WORK=$WORK
-gobind -lang=go,objc -outdir=$WORK{{if .Prefix}} -prefix={{.Prefix}}{{end}} golang.org/x/mobile/asset
+GOOS=darwin gobind -lang=go,objc -outdir=$WORK{{if .Prefix}} -prefix={{.Prefix}}{{end}} golang.org/x/mobile/asset
 GOARM=7 GOOS=darwin GOARCH=arm CC=clang-iphoneos CXX=clang-iphoneos CGO_CFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_LDFLAGS=-isysroot=iphoneos -miphoneos-version-min=6.1 -arch armv7 CGO_ENABLED=1 GOPATH=$WORK:$GOPATH go build -tags ios -x -buildmode=c-archive -o $WORK/asset-arm.a gobind
 rm -r -f "Asset.framework"
 mkdir -p Asset.framework/Versions/A/Headers