diff --git a/CleanSpec.mk b/CleanSpec.mk
index 3918fce..025edb0 100644
--- a/CleanSpec.mk
+++ b/CleanSpec.mk
@@ -289,6 +289,11 @@
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/root/default.prop)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/recovery/root/default.prop)
 
+# API 21?
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/build.prop)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/app/*)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/APPS/*)
+
 # ************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
 # ************************************************
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 31c3242..ea10f2a 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -53,7 +53,7 @@
   # intermediate builds).  During development, this number remains at the
   # SDK version the branch is based on and PLATFORM_VERSION_CODENAME holds
   # the code-name of the new development work.
-  PLATFORM_SDK_VERSION := 20
+  PLATFORM_SDK_VERSION := 21
 endif
 
 ifeq "" "$(PLATFORM_VERSION_CODENAME)"