diff --git a/device-omni.mk b/device-omni.mk
index 87934bc..2ed29e5 100644
--- a/device-omni.mk
+++ b/device-omni.mk
@@ -10,4 +10,14 @@
 
 # EUICC
 PRODUCT_PACKAGES += \
-    EuiccSupportPixelOverlay
\ No newline at end of file
+    EuiccSupportPixelOverlay
+
+# custom A/B postinstall
+PRODUCT_PACKAGES += \
+    omnipreopt_script
+
+AB_OTA_POSTINSTALL_CONFIG += \
+    RUN_POSTINSTALL_system=true \
+    POSTINSTALL_PATH_system=system/bin/omnipreopt_script \
+    FILESYSTEM_TYPE_system=ext4 \
+    POSTINSTALL_OPTIONAL_system=true
diff --git a/device.mk b/device.mk
index e0dcc91..3821c0c 100644
--- a/device.mk
+++ b/device.mk
@@ -50,7 +50,8 @@
 LOCAL_64ONLY := _64
 endif
 
-AB_OTA_POSTINSTALL_CONFIG += \
+# replaced from device-omni.mk
+#AB_OTA_POSTINSTALL_CONFIG += \
 	RUN_POSTINSTALL_system=true \
 	POSTINSTALL_PATH_system=system/bin/otapreopt_script \
 	FILESYSTEM_TYPE_system=ext4 \