diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 748eedb..06fb1dd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,7 @@ jobs:
     # Whenever the Go version is updated here, .promu.yml
     # should also be updated.
     container:
-      image: quay.io/prometheus/golang-builder:1.22-base
+      image: quay.io/prometheus/golang-builder:1.21-base
     steps:
       - uses: actions/checkout@v4
       - uses: prometheus/promci@v0.1.0
@@ -40,7 +40,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v5
         with:
-          go-version: '<1.22'
+          go-version: '<1.21'
       - name: Lint
         uses: golangci/golangci-lint-action@v4.0.0
         with:
diff --git a/.promu.yml b/.promu.yml
index 2d13006..b90b9c4 100644
--- a/.promu.yml
+++ b/.promu.yml
@@ -1,7 +1,7 @@
 go:
     # Whenever the Go version is updated here,
     # .github/workflows/ci.yml should also be updated.
-    version: 1.22
+    version: 1.21
     # cgo: false
 repository:
     path: github.com/Lusitaniae/apache_exporter