diff --git a/core/build_id.mk b/core/build_id.mk
index ba5ca42..2f9c3f3 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -18,4 +18,4 @@
 # (like "CRB01").  It must be a single word, and is
 # capitalized by convention.
 
-BUILD_ID=AOSP.MASTER
+BUILD_ID=MASTER
diff --git a/core/tasks/cts.mk b/core/tasks/cts.mk
index fdd9591..dccf14f 100644
--- a/core/tasks/cts.mk
+++ b/core/tasks/cts.mk
@@ -25,3 +25,35 @@
 
 .PHONY: cts_v2
 cts_v2: cts
+
+# platform version check (b/32056228)
+# ============================================================
+ifneq (,$(wildcard cts/))
+  cts_platform_version_path := cts/tests/tests/os/assets/platform_versions.txt
+  cts_platform_version_string := $(shell cat $(cts_platform_version_path))
+  cts_platform_release_path := cts/tests/tests/os/assets/platform_releases.txt
+  cts_platform_release_string := $(shell cat $(cts_platform_release_path))
+
+  ifeq (,$(findstring $(PLATFORM_VERSION),$(cts_platform_version_string)))
+    define error_msg
+      ============================================================
+      Could not find version "$(PLATFORM_VERSION)" in CTS platform version file:
+      $(cts_platform_version_path)
+      Most likely PLATFORM_VERSION in build/core/version_defaults.mk
+      has changed and a new version must be added to this CTS file.
+      ============================================================
+    endef
+    $(error $(error_msg))
+  endif
+  ifeq (,$(findstring $(PLATFORM_VERSION_LAST_STABLE),$(cts_platform_release_string)))
+    define error_msg
+      ============================================================
+      Could not find version "$(PLATFORM_VERSION_LAST_STABLE)" in CTS platform release file:
+      $(cts_platform_release_path)
+      Most likely PLATFORM_VERSION_LAST_STABLE in build/core/version_defaults.mk
+      has changed and a new version must be added to this CTS file.
+      ============================================================
+    endef
+    $(error $(error_msg))
+  endif
+endif
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 5ee918e..8eac1ac 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -246,7 +246,7 @@
     #  It must be of the form "YYYY-MM-DD" on production devices.
     #  It must match one of the Android Security Patch Level strings of the Public Security Bulletins.
     #  If there is no $PLATFORM_SECURITY_PATCH set, keep it empty.
-      PLATFORM_SECURITY_PATCH := 2021-09-05
+      PLATFORM_SECURITY_PATCH := 2021-10-05
 endif
 .KATI_READONLY := PLATFORM_SECURITY_PATCH
 
diff --git a/target/product/gsi_release.mk b/target/product/gsi_release.mk
index bd7c4ab..09417b5 100644
--- a/target/product/gsi_release.mk
+++ b/target/product/gsi_release.mk
@@ -62,8 +62,12 @@
     init.gsi.rc \
     init.vndk-nodef.rc \
 
-# Support additional P, Q and R VNDK packages
-PRODUCT_EXTRA_VNDK_VERSIONS := 28 29 30
+# Support additional VNDK snapshots
+PRODUCT_EXTRA_VNDK_VERSIONS := \
+    28 \
+    29 \
+    30 \
+    31 \
 
 # Do not build non-GSI partition images.
 PRODUCT_BUILD_CACHE_IMAGE := false