diff --git a/core/main.mk b/core/main.mk
index 56c193ba1..25cc80618 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -1183,9 +1183,10 @@ APEX_MODULE_LIBS += \
 # still may create these libraries in /system (b/129006418).
 DISABLE_APEX_LIBS_ABSENCE_CHECK ?=
 
-# Allow APEX libraries under /system/apex, which happens when APEX flattening
-# is enabled.
-APEX_LIBS_ABSENCE_CHECK_EXCLUDE := apex
+# Allow APEX libraries under:
+# /system/apex, which happens when APEX flattening is enabled.
+# /system/system_ext, which happens with GSI
+APEX_LIBS_ABSENCE_CHECK_EXCLUDE := apex system_ext
 
 # Bionic should not be in /system, except for the bootstrap instance.
 APEX_LIBS_ABSENCE_CHECK_EXCLUDE += lib/bootstrap lib64/bootstrap
diff --git a/core/product.mk b/core/product.mk
index 2276db24d..c7aac000c 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -381,6 +381,8 @@ _product_single_value_vars += PRODUCT_VIRTUAL_AB_OTA_RETROFIT
 # If set, Java module in product partition cannot use hidden APIs.
 _product_single_value_vars += PRODUCT_ENFORCE_PRODUCT_PARTITION_INTERFACE
 
+_product_single_value_vars += PRODUCT_INSTALL_EXTRA_FLATTENED_APEXES
+
 .KATI_READONLY := _product_single_value_vars _product_list_vars
 _product_var_list :=$= $(_product_single_value_vars) $(_product_list_vars)
 
diff --git a/core/soong_config.mk b/core/soong_config.mk
index 7ce59f155..85e7bbc9f 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -199,6 +199,8 @@ $(call end_json_map)
 
 $(call add_json_bool, EnforceProductPartitionInterface,  $(PRODUCT_ENFORCE_PRODUCT_PARTITION_INTERFACE))
 
+$(call add_json_bool, InstallExtraFlattenedApexes, $(PRODUCT_INSTALL_EXTRA_FLATTENED_APEXES))
+
 $(call json_end)
 
 $(file >$(SOONG_VARIABLES).tmp,$(json_contents))
diff --git a/target/product/gsi_release.mk b/target/product/gsi_release.mk
index aee7959a8..a6dd4183c 100644
--- a/target/product/gsi_release.mk
+++ b/target/product/gsi_release.mk
@@ -38,6 +38,12 @@ PRODUCT_USE_DYNAMIC_PARTITION_SIZE := true
 # Needed by Pi newly launched device to pass VtsTrebleSysProp on GSI
 PRODUCT_COMPATIBLE_PROPERTY_OVERRIDE := true
 
+# GSI targets should install "unflattened" APEXes in /system
+TARGET_FLATTEN_APEX := false
+
+# GSI targets should install "flattened" APEXes in /system_ext as well
+PRODUCT_INSTALL_EXTRA_FLATTENED_APEXES := true
+
 # GSI specific tasks on boot
 PRODUCT_PACKAGES += \
     gsi_skip_mount.cfg \
diff --git a/target/product/mainline_system.mk b/target/product/mainline_system.mk
index 5a5c17d35..20bdc9f5b 100644
--- a/target/product/mainline_system.mk
+++ b/target/product/mainline_system.mk
@@ -21,6 +21,9 @@ $(call inherit-product, $(SRC_TARGET_DIR)/product/languages_default.mk)
 # Add adb keys to debuggable AOSP builds (if they exist)
 $(call inherit-product-if-exists, vendor/google/security/adb/vendor_key.mk)
 
+# Enable updating of APEXes
+$(call inherit-product, $(SRC_TARGET_DIR)/product/updatable_apex.mk)
+
 # Shared java libs
 PRODUCT_PACKAGES += \
     com.android.nfc_extras \