diff --git a/.github/workflows/docker-action.yml b/.github/workflows/docker-action.yml
index dc43cf0..efa22fb 100644
--- a/.github/workflows/docker-action.yml
+++ b/.github/workflows/docker-action.yml
@@ -7,7 +7,7 @@ on:
   #   - cron: '0 4 * * *'
   push:
     branches:
-      - master
+      - v8.20
   pull_request:
     branches:
       - '**'
@@ -18,20 +18,27 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
+        coq_version:
+          - '8.20.dev'
         image:
-          - 'coqorg/coq:dev'
+          # we can't use coqorg/coq images to test bignums
+          # since these images already include coq-bignums
+          - 'coqorg/base:4.13.1-flambda'
       fail-fast: false
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: coq-community/docker-coq-action@v1
         with:
           opam_file: 'coq-bignums.opam'
           custom_image: ${{ matrix.image }}
           install: |
-            startGroup "Install dependencies"
-              # sudo apt-get update -y -q
-              opam remove -y coq-bignums # remove coq-bignums already in image
-              opam pin add -n -y -k path $PACKAGE $WORKDIR
+            startGroup "Install coq and dependencies"
+              sudo apt-get update -y -q
+              opam remove -y coq-bignums || true # remove coq-bignums if ever in image
+              opam repository add --all-switches --set-default coq-extra-dev https://coq.inria.fr/opam/extra-dev # docker-coq
+              opam repository add --all-switches --set-default coq-core-dev https://coq.inria.fr/opam/core-dev # docker-coq
+              opam pin add -n -y -k version coq ${{ matrix.coq_version }} # docker-coq
+              opam pin add -n -y -k path $PACKAGE.dev $WORKDIR
               opam update -y
               opam install --confirm-level=unsafe-yes -j 2 $PACKAGE --deps-only
             endGroup
diff --git a/README.md b/README.md
index 5688d0c..4f23b9d 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ Follow the instructions on https://github.com/coq-community/templates to regener
 [![Code of Conduct][conduct-shield]][conduct-link]
 [![Zulip][zulip-shield]][zulip-link]
 
-[docker-action-shield]: https://github.com/coq-community/bignums/actions/workflows/docker-action.yml/badge.svg?branch=master
+[docker-action-shield]: https://github.com/coq-community/bignums/actions/workflows/docker-action.yml/badge.svg?branch=v8.20
 [docker-action-link]: https://github.com/coq-community/bignums/actions/workflows/docker-action.yml
 
 [contributing-shield]: https://img.shields.io/badge/contributions-welcome-%23f7931e.svg
diff --git a/coq-bignums.opam b/coq-bignums.opam
index 16e28ce..c6339d9 100644
--- a/coq-bignums.opam
+++ b/coq-bignums.opam
@@ -1,6 +1,9 @@
+# This file was generated from `meta.yml`, please do not edit manually.
+# Follow the instructions on https://github.com/coq-community/templates to regenerate.
+
 opam-version: "2.0"
 maintainer: "palmskog@gmail.com"
-version: "dev"
+version: "8.20.dev"
 
 homepage: "https://github.com/coq-community/bignums"
 dev-repo: "git+https://github.com/coq-community/bignums.git"
@@ -19,7 +22,7 @@ install: [
 ]
 depends: [
   "ocaml"
-  "coq" {= "dev"}
+  "coq" {>= "8.20" & < "8.21~"}
 ]
 
 tags: [
diff --git a/meta.yml b/meta.yml
index daa00ca..1e71809 100644
--- a/meta.yml
+++ b/meta.yml
@@ -4,7 +4,7 @@ shortname: bignums
 organization: coq-community
 community: true
 action: true
-branch: master
+branch: v8.20
 
 synopsis: >-
   Bignums, the Coq library of arbitrarily large numbers
@@ -28,7 +28,7 @@ maintainers:
 
 opam-file-maintainer: palmskog@gmail.com
 
-opam-file-version: dev
+opam-file-version: 8.20.dev
 
 license:
   fullname: GNU Lesser General Public License v2.1
@@ -41,10 +41,10 @@ supported_ocaml_versions:
 
 supported_coq_versions:
   text: master (use the corresponding branch or release for other Coq versions)
-  opam: '{= "dev"}'
+  opam: '{>= "8.20" & < "8.21~"}'
 
 tested_coq_opam_versions:
-- version: dev
+- version: 8.20
 
 ci_cron_schedule: '0 4 * * *'