diff --git a/.tool-versions b/.tool-versions
new file mode 100644
index 0000000..bb46032
--- /dev/null
+++ b/.tool-versions
@@ -0,0 +1 @@
+golang 1.18.10
diff --git a/README.md b/README.md
index 202bea6..875540c 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,10 @@
 This app has three components: the GitHub Action repo, the intermediate server, and the Slack interface.
 It is recommended to create your own repo to test the app, using the 2,000 free minutes they give you every month.
 
+## Prerequisite
+
+- Go 1.18 (via asdf)
+
 ### Running local development server
 
 On root directory:
@@ -54,4 +58,4 @@ If you want to disable config persistence i.e. reconstruct the list of subscribe
 
 Under `config.toml` -> `[store]`,  change `type` to `"InMemory"`. 
 
-8. Test the app **in a public channel** (e.g. #team-bot-sandbox). The app was not designed with direct messages in mind and may not work there.
\ No newline at end of file
+8. Test the app **in a public channel** (e.g. #team-bot-sandbox). The app was not designed with direct messages in mind and may not work there.