diff --git a/sdk/bp.go b/sdk/bp.go
index 6936daf..5c340cd 100644
--- a/sdk/bp.go
+++ b/sdk/bp.go
@@ -48,8 +48,7 @@
 }
 
 func (s *bpPropertySet) AddPropertySet(name string) android.BpPropertySet {
-	set := &bpPropertySet{}
-	set.init()
+	set := newPropertySet()
 	s.AddProperty(name, set)
 	return set
 }
@@ -62,7 +61,7 @@
 	return s.tags[name]
 }
 
-func (s *bpPropertySet) transform(transformer bpPropertyTransformer) {
+func (s *bpPropertySet) transformContents(transformer bpPropertyTransformer) {
 	var newOrder []string
 	for _, name := range s.order {
 		value := s.properties[name]
@@ -70,7 +69,13 @@
 		var newValue interface{}
 		var newTag android.BpPropertyTag
 		if propertySet, ok := value.(*bpPropertySet); ok {
-			newValue, newTag = transformer.transformPropertySet(name, propertySet, tag)
+			var newPropertySet *bpPropertySet
+			newPropertySet, newTag = transformPropertySet(transformer, name, propertySet, tag)
+			if newPropertySet == nil {
+				newValue = nil
+			} else {
+				newValue = newPropertySet
+			}
 		} else {
 			newValue, newTag = transformer.transformProperty(name, value, tag)
 		}
@@ -88,6 +93,14 @@
 	s.order = newOrder
 }
 
+func transformPropertySet(transformer bpPropertyTransformer, name string, propertySet *bpPropertySet, tag android.BpPropertyTag) (*bpPropertySet, android.BpPropertyTag) {
+	newPropertySet, newTag := transformer.transformPropertySet(name, propertySet, tag)
+	if newPropertySet != nil {
+		newPropertySet.transformContents(transformer)
+	}
+	return newPropertySet, newTag
+}
+
 func (s *bpPropertySet) setProperty(name string, value interface{}) {
 	if s.properties[name] == nil {
 		s.AddProperty(name, value)
@@ -180,8 +193,7 @@
 func (m *bpModule) transform(transformer bpTransformer) *bpModule {
 	transformedModule := transformer.transformModule(m)
 	// Copy the contents of the returned property set into the module and then transform that.
-	transformedModule.bpPropertySet, _ = transformer.transformPropertySet("", transformedModule.bpPropertySet, nil)
-	transformedModule.bpPropertySet.transform(transformer)
+	transformedModule.bpPropertySet, _ = transformPropertySet(transformer, "", transformedModule.bpPropertySet, nil)
 	return transformedModule
 }
 
@@ -253,10 +265,19 @@
 }
 
 func (f *bpFile) newModule(moduleType string) *bpModule {
+	return newModule(moduleType)
+}
+
+func newModule(moduleType string) *bpModule {
 	module := &bpModule{
 		moduleType:    moduleType,
-		bpPropertySet: &bpPropertySet{},
+		bpPropertySet: newPropertySet(),
 	}
-	module.bpPropertySet.init()
 	return module
 }
+
+func newPropertySet() *bpPropertySet {
+	set := &bpPropertySet{}
+	set.init()
+	return set
+}