diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index d78148c8fb6f..4c3a95e48246 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -256,6 +256,7 @@ jobs:
            github.event_name == 'pull_request'
            && !contains(github.event.pull_request.body, '[skip ci]')
            && !contains(github.event.pull_request.body, '[skip community_build]')
+           && !contains(github.event.pull_request.body, '[skip community_build_a]')
          )
          || (
            github.event_name == 'workflow_dispatch'
@@ -263,6 +264,9 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 15 as default
+        run: echo "/usr/lib/jvm/java-15-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: git -c "http.https://github.com/.extraheader=" fetch --recurse-submodules=no "https://github.com/lampepfl/dotty" && git reset --hard FETCH_HEAD || true
 
@@ -303,6 +307,7 @@ jobs:
            github.event_name == 'pull_request'
            && !contains(github.event.pull_request.body, '[skip ci]')
            && !contains(github.event.pull_request.body, '[skip community_build]')
+           && !contains(github.event.pull_request.body, '[skip community_build_b]')
          )
          || (
            github.event_name == 'workflow_dispatch'
@@ -310,6 +315,9 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 15 as default
+        run: echo "/usr/lib/jvm/java-15-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: git -c "http.https://github.com/.extraheader=" fetch --recurse-submodules=no "https://github.com/lampepfl/dotty" && git reset --hard FETCH_HEAD || true
 
@@ -350,6 +358,7 @@ jobs:
            github.event_name == 'pull_request'
            && !contains(github.event.pull_request.body, '[skip ci]')
            && !contains(github.event.pull_request.body, '[skip community_build]')
+           && !contains(github.event.pull_request.body, '[skip community_build_c]')
          )
          || (
            github.event_name == 'workflow_dispatch'
@@ -357,6 +366,9 @@ jobs:
          )"
 
     steps:
+      - name: Set JDK 16 as default
+        run: echo "/usr/lib/jvm/java-16-openjdk-amd64/bin" >> $GITHUB_PATH
+
       - name: Reset existing repo
         run: git -c "http.https://github.com/.extraheader=" fetch --recurse-submodules=no "https://github.com/lampepfl/dotty" && git reset --hard FETCH_HEAD || true