diff --git a/BoardConfigCommon.mk b/BoardConfigCommon.mk
index 78f7a4c..dc841bf 100644
--- a/BoardConfigCommon.mk
+++ b/BoardConfigCommon.mk
@@ -4,6 +4,10 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 
+# Security - must be defined before including BoardConfig-common.mk
+BOOT_SECURITY_PATCH := 2025-09-05
+VENDOR_SECURITY_PATCH := $(BOOT_SECURITY_PATCH)
+
 include device/google/gs101/BoardConfig-common.mk
 
 # Kernel