diff --git a/core/Makefile b/core/Makefile
index ee8c6fa..cdb8423 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -6132,6 +6132,12 @@
     $(BUILT_TARGET_FILES_DIR): $(TARGET_OUT_OEM)/$(OSRELEASED_DIRECTORY)/product_version
     $(BUILT_TARGET_FILES_DIR): $(TARGET_OUT_ETC)/$(OSRELEASED_DIRECTORY)/system_version
   endif
+
+  # Not checking in board_config.mk, since AB_OTA_PARTITIONS may be updated in Android.mk (e.g. to
+  # additionally include radio or bootloader partitions).
+  ifeq ($(AB_OTA_PARTITIONS),)
+    $(error AB_OTA_PARTITIONS must be defined when using AB_OTA_UPDATER)
+  endif
 endif
 
 ifneq ($(AB_OTA_PARTITIONS),)
diff --git a/core/board_config.mk b/core/board_config.mk
index d3f0493..e184601 100644
--- a/core/board_config.mk
+++ b/core/board_config.mk
@@ -923,9 +923,7 @@
 ###########################################
 # Ensure consistency among TARGET_RECOVERY_UPDATER_LIBS, AB_OTA_UPDATER, and PRODUCT_OTA_FORCE_NON_AB_PACKAGE.
 TARGET_RECOVERY_UPDATER_LIBS ?=
-ifeq ($(AB_OTA_UPDATER),)
-AB_OTA_UPDATER := true
-endif
+AB_OTA_UPDATER ?=
 .KATI_READONLY := TARGET_RECOVERY_UPDATER_LIBS AB_OTA_UPDATER
 
 # Ensure that if PRODUCT_OTA_FORCE_NON_AB_PACKAGE == true, then AB_OTA_UPDATER must be true