diff --git a/core/Makefile b/core/Makefile
index 882c138..c5ea43e 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -181,6 +181,8 @@
 			BUILD_DISPLAY_ID="$(BUILD_DISPLAY_ID)" \
 			BUILD_NUMBER="$(BUILD_NUMBER)" \
 			PLATFORM_VERSION="$(PLATFORM_VERSION)" \
+			PLATFORM_SECURITY_PATCH="$(PLATFORM_SECURITY_PATCH)" \
+			PLATFORM_BASE_OS="$(PLATFORM_BASE_OS)" \
 			PLATFORM_SDK_VERSION="$(PLATFORM_SDK_VERSION)" \
 			PLATFORM_VERSION_CODENAME="$(PLATFORM_VERSION_CODENAME)" \
 			BUILD_VERSION_TAGS="$(BUILD_VERSION_TAGS)" \
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 51a8382..7cf6387 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -24,6 +24,7 @@
 #     DEFAULT_APP_TARGET_SDK
 #     BUILD_ID
 #     BUILD_NUMBER
+#     SECURITY_PATCH
 #
 
 # Look for an optional file containing overrides of the defaults,
@@ -62,6 +63,22 @@
   PLATFORM_VERSION_CODENAME := REL
 endif
 
+ifeq "" "$(PLATFORM_SECURITY_PATCH)"
+  # Used to indicate the security patch that has been applied to the device.
+  # Can be an arbitrary string, but must be a single word.
+  #
+  # If there is no $PLATFORM_SECURITY_PATCH set, keep it empty.
+  PLATFORM_SECURITY_PATCH := 2015-11-01
+endif
+
+ifeq "" "$(PLATFORM_BASE_OS)"
+  # Used to indicate the base os applied to the device.
+  # Can be an arbitrary string, but must be a single word.
+  #
+  # If there is no $PLATFORM_BASE_OS set, keep it empty.
+  PLATFORM_BASE_OS :=
+endif
+
 ifeq "" "$(DEFAULT_APP_TARGET_SDK)"
   # This is the default minSdkVersion and targetSdkVersion to use for
   # all .apks created by the build system.  It can be overridden by explicitly