diff --git a/CommonInstaller b/CommonInstaller
index f906976..509bbf5 100644
--- a/CommonInstaller
+++ b/CommonInstaller
@@ -210,6 +210,8 @@ mount_partitions () {
 		mount --move /system /system_root
 		mount -o bind /system_root/system /system
 	fi
+
+	[ ! -f /system/build.prop ] && error "failed to mount /system (unsupported A/B device?)"
 }
 
 detect_mode () {