diff --git a/Dockerfile b/Dockerfile
index be412e0..cd19e78 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,3 @@
-# syntax=docker/dockerfile-upstream:master
 ARG CNPG_TAG
 
 FROM ghcr.io/cloudnative-pg/postgresql:$CNPG_TAG
diff --git a/README.md b/README.md
index bf974ca..788d446 100644
--- a/README.md
+++ b/README.md
@@ -26,4 +26,9 @@ Container images for [cloudnative-pg](https://cloudnative-pg.io/) with the [pgve
 >     initdb:
 >       postInitSQL:
 >         - ALTER SYSTEM SET search_path TO "$user", public, vectors;
->         - CREATE EXTENSION IF NOT EXISTS "vectors";
\ No newline at end of file
+>         - CREATE EXTENSION IF NOT EXISTS "vectors";
+
+## Building
+
+To build the Dockerfile locally, you need to pass the `CNPG_TAG` and `PGVECTORS_TAG` args. For example:  
+`docker build . --build-arg="CNPG_TAG=16.3" --build-arg="PGVECTORS_TAG=v0.2.1"`
\ No newline at end of file