diff --git a/core/product.mk b/core/product.mk
index c54583d..3d54719 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -368,6 +368,12 @@
 # Whether the product would like to check prebuilt ELF files.
 _product_single_value_vars += PRODUCT_CHECK_ELF_FILES
 
+# If set, device uses virtual A/B.
+_product_single_value_vars += PRODUCT_VIRTUAL_AB_OTA
+
+# If set, device retrofits virtual A/B.
+_product_single_value_vars += PRODUCT_VIRTUAL_AB_OTA_RETROFIT
+
 .KATI_READONLY := _product_single_value_vars _product_list_vars
 _product_var_list :=$= $(_product_single_value_vars) $(_product_list_vars)