diff --git a/android/androidmk.go b/android/androidmk.go
index 19d5ea6..aff43fa 100644
--- a/android/androidmk.go
+++ b/android/androidmk.go
@@ -53,13 +53,13 @@
 
 type AndroidMkExtraFunc func(w io.Writer, outputFile Path)
 
-func AndroidMkSingleton() blueprint.Singleton {
+func AndroidMkSingleton() Singleton {
 	return &androidMkSingleton{}
 }
 
 type androidMkSingleton struct{}
 
-func (c *androidMkSingleton) GenerateBuildActions(ctx blueprint.SingletonContext) {
+func (c *androidMkSingleton) GenerateBuildActions(ctx SingletonContext) {
 	config := ctx.Config().(Config)
 
 	if !config.EmbeddedInMake() {
@@ -68,10 +68,8 @@
 
 	var androidMkModulesList []Module
 
-	ctx.VisitAllModules(func(module blueprint.Module) {
-		if amod, ok := module.(Module); ok {
-			androidMkModulesList = append(androidMkModulesList, amod)
-		}
+	ctx.VisitAllModules(func(module Module) {
+		androidMkModulesList = append(androidMkModulesList, module)
 	})
 
 	sort.Sort(AndroidModulesByName{androidMkModulesList, ctx})
@@ -86,14 +84,13 @@
 		ctx.Errorf(err.Error())
 	}
 
-	ctx.Build(pctx, blueprint.BuildParams{
-		Rule:     blueprint.Phony,
-		Outputs:  []string{transMk.String()},
-		Optional: true,
+	ctx.Build(pctx, BuildParams{
+		Rule:   blueprint.Phony,
+		Output: transMk,
 	})
 }
 
-func translateAndroidMk(ctx blueprint.SingletonContext, mkFile string, mods []Module) error {
+func translateAndroidMk(ctx SingletonContext, mkFile string, mods []Module) error {
 	buf := &bytes.Buffer{}
 
 	fmt.Fprintln(buf, "LOCAL_MODULE_MAKEFILE := $(lastword $(MAKEFILE_LIST))")
@@ -145,7 +142,7 @@
 	return ioutil.WriteFile(mkFile, buf.Bytes(), 0666)
 }
 
-func translateAndroidMkModule(ctx blueprint.SingletonContext, w io.Writer, mod blueprint.Module) error {
+func translateAndroidMkModule(ctx SingletonContext, w io.Writer, mod blueprint.Module) error {
 	provider, ok := mod.(AndroidMkDataProvider)
 	if !ok {
 		return nil