diff --git a/.tool-versions b/.tool-versions
index c7cd797..2f740c1 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1 +1,2 @@
+golang 1.21.13
 yarn 1.22.19
diff --git a/Dockerfile b/Dockerfile
index 55708f0..b68b7ad 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -25,7 +25,7 @@ RUN yarn install && yarn build
 # Building a backend.
 #
 
-FROM --platform=linux/amd64 golang:1.21-alpine AS backend
+FROM --platform=linux/amd64 golang:1.21.13-alpine AS backend
 
 # Move to a working directory (/build).
 WORKDIR /build
diff --git a/go.mod b/go.mod
index 55bfd36..9811c5f 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/platacard/asynqmon
 
-go 1.21
+go 1.21.13
 
 require (
 	github.com/google/go-cmp v0.5.6