diff --git a/Makefile b/Makefile
index 7bfd8bf..d2aa644 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,8 @@ check:
 	python3 -m pylint app/
 
 docker:
-	docker build -t ${REPO_OWNER_LOWER}/${REPO_NAME_SNAKE} .
+	python3 -m dotenv -f version_code run \
+	docker build -t ${REPO_OWNER_LOWER}/${REPO_NAME_SNAKE}:$$VERSION .
 
 clean:
 	rm -rf app/__pycache__
diff --git a/README.md b/README.md
index 5cf118c..a463a5b 100644
--- a/README.md
+++ b/README.md
@@ -32,7 +32,8 @@ corresponding to your database structure
 as explained below ([Structure > Database](#database))
 7. Check if `Makefile`, `Dockerfile`, `docker-compose.yml` are correct
 8. Run the formatter and linters (`make format`, then `make check`)
-9. Build a docker image and [publish](#publishing-app) it
+9. Edit the `version_code` file if needed,
+build a docker image and [publish](#publishing-app) it
 
 ### Makefile
 Make commands:
diff --git a/version_code b/version_code
new file mode 100644
index 0000000..aa40e78
--- /dev/null
+++ b/version_code
@@ -0,0 +1,3 @@
+# Your app's version code:
+# (used as a docker image tag)
+VERSION=1.0.0