diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 000000000..a465ad02a
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,31 @@
+name: Ocaml CI
+
+on:
+  - pull_request
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout tree
+        uses: actions/checkout@v4
+
+        # We don't want to init all submodules as some are private.
+      - name: Init ir-calcul submodule
+        run:
+          git submodule init ir-calcul
+
+          git submodule update ir-calcul
+
+      - name: Set-up Ocaml
+        uses: ocaml/setup-ocaml@v3
+        with:
+          ocaml-compiler: 4.14.2
+          opam-pin: false
+
+      - run: opam install . --deps-only
+
+      - run: opam exec -- dune build
+
+      - run: opam exec -- make tests
diff --git a/.ocamlformat b/.ocamlformat
index 3e17117d7..4c54de3de 100644
--- a/.ocamlformat
+++ b/.ocamlformat
@@ -1,4 +1,4 @@
 profile = default
 margin = 80
 exp-grouping = preserve
-version=0.19.0
+module-item-spacing = sparse
diff --git a/dune-project b/dune-project
index 5e5a380f5..810c65c99 100644
--- a/dune-project
+++ b/dune-project
@@ -6,8 +6,8 @@
 
 (generate_opam_files true)
 
-(source
- (uri git+https://github.com/MLanguage/mlang.git))
+;(source
+; (uri git+https://github.com/MLanguage/mlang.git))
 
 (homepage https://github.com/MLanguage/mlang)
 
@@ -67,4 +67,4 @@
   (odoc
    (>= 1.5.3))
   (ocamlformat
-   (= 0.19.0))))
\ No newline at end of file
+   (= 0.19.0))))
diff --git a/irj_checker.opam b/irj_checker.opam
index a69161ade..017c505c2 100644
--- a/irj_checker.opam
+++ b/irj_checker.opam
@@ -13,7 +13,7 @@ depends: [
   "ocaml" {>= "4.11.2"}
   "dune" {build}
   "odoc" {>= "1.5.3"}
-  "ocamlformat" {= "0.19.0"}
+  "ocamlformat" {<= "0.20.0"}
 ]
 build: [
   ["dune" "subst"] {pinned}
diff --git a/mlang.opam b/mlang.opam
index 6bc3b41c4..1edd97d16 100644
--- a/mlang.opam
+++ b/mlang.opam
@@ -25,7 +25,7 @@ depends: [
   "dune-build-info" {= "2.5.1"}
   "num" {>= "1.3"}
   "mlgmpidl" {>= "1.2.12"}
-  "ocamlformat" {= "0.19.0"}
+  "ocamlformat" {<= "0.20.0"}
   "parmap" {= "1.2.3"}
 ]
 build: [