diff --git a/.github/workflows/master.yml b/.github/workflows/master.yml
index 2282dcfd..8f193801 100644
--- a/.github/workflows/master.yml
+++ b/.github/workflows/master.yml
@@ -22,11 +22,13 @@ jobs:
       matrix:
         os:
           - ubuntu-latest
-
+    concurrency:
+      group: ${{ github.workflow }}-${{ github.ref }}
+      cancel-in-progress: true
     runs-on: ${{ matrix.os }}
     container:
       image: ocaml/opam:ubuntu-lts-ocaml-4.14
-      options: --user root               # dirty hack
+      options: --user opam               # dirty hack
 
     steps:
       - name: Cancel Previous Runs
@@ -42,12 +44,17 @@ jobs:
           sudo apt-get install pkg-config libpcre2-dev m4 -y
       - run: opam --version
 
-      - run: |
-          git config --global --add safe.directory /__w/GT/GT
-          git submodule update --init
+      - name: bisect many not work without it
         if: false
+        run: |
+          git config --global --add safe.directory /__w/GT/GT
+          #git submodule update --init
+
       - run: opam pin add GT . --no-action
+        if: false
+
       - run: opam depext GT --yes #--with-test
+        if: false
 
       - name: Install dependecies for documentation
         run: |
@@ -77,6 +84,12 @@ jobs:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./_build/default/_doc/_html
 
+- name: Build API documentation
+if: github.event_name != 'pull_request'
+run: |
+opam exec -- make install odig
+echo "ODIG_DOC_LOC=$(opam exec -- odig cache path)/html" >> $GITHUB_ENV
+
       - name: Send coverage report to Coveralls
         run: |
           #git config --global --add safe.directory /__w/zanuda/zanuda
diff --git a/.github/workflows/master52.yml b/.github/workflows/master52.yml
index 75bb4791..ba37163c 100644
--- a/.github/workflows/master52.yml
+++ b/.github/workflows/master52.yml
@@ -43,10 +43,9 @@ jobs:
       - run: opam --version
 
       - name: Update submodules
-        if: false
         run: |
           git config --global --add safe.directory /__w/GT/GT
-          git submodule update --init
+          #git submodule update --init
 
       - run: opam pin add GT . --no-action
         if: false
diff --git a/GT.opam b/GT.opam
index c0ffebf3..c2e1bce6 100644
--- a/GT.opam
+++ b/GT.opam
@@ -34,6 +34,7 @@ depends: [
   "conf-m4" {build}
   "odoc" {with-doc}
   "odig" {with-doc}
+  "pa-ppx" {with-doc}
 ]
 build: [
   ["dune" "subst"] {dev}
diff --git a/dune-project b/dune-project
index 71ea235b..37b700c5 100644
--- a/dune-project
+++ b/dune-project
@@ -45,6 +45,7 @@
   (conf-m4 :build)
   (odoc :with-doc)
   (odig :with-doc)
+  (pa-ppx :with-doc)
   ;
   ))