diff --git a/README.md b/README.md
index 296e50d..22cebb5 100644
--- a/README.md
+++ b/README.md
@@ -61,14 +61,16 @@ To install `pg_ivm`, execute this in the module's directory:
 make install USE_PGXS=1
 ```
 
+If you installed PostgreSQL from rpm or deb, you will need the devel package (for example, postgresql14-devel or postgresql-server-dev-14).
+
+> **Important:** Don't forget to set the `PG_CONFIG` variable (`make PG_CONFIG=...`) in case you want to test `pg_ivm` on a non-default or custom build of PostgreSQL. Read more [here](https://wiki.postgresql.org/wiki/Building_and_Installing_PostgreSQL_Extension_Modules).
+
 And, execute CREATE EXTENSION comand.
 
 ```
 CREATE EXTENSION pg_ivm;
 ```
 
-> **Important:** Don't forget to set the `PG_CONFIG` variable (`make PG_CONFIG=...`) in case you want to test `pg_ivm` on a non-default or custom build of PostgreSQL. Read more [here](https://wiki.postgresql.org/wiki/Building_and_Installing_PostgreSQL_Extension_Modules).
-
 ## Objects
 
 When `pg_ivm` is installed, the following objects are created.