diff --git a/.github/workflows/test-alt-ergo.yml b/.github/workflows/test-alt-ergo.yml
index 1d52b813..334d32ba 100644
--- a/.github/workflows/test-alt-ergo.yml
+++ b/.github/workflows/test-alt-ergo.yml
@@ -1,15 +1,12 @@
 name: Test Alt-Ergo
 
 on:
-  push:
-    branches:
-      - main
   pull_request:
-    branches:
-      - main
+    types: [ labeled ]
 
 jobs:
   test-alt-ergo:
+    if: contains(github.event.pull_request.labels.*.name, 'alt-ergo')
     runs-on: ubuntu-latest
     env:
       OPAMCONFIRMLEVEL: unsafe-yes
diff --git a/.github/workflows/test-bitwuzla.yml b/.github/workflows/test-bitwuzla.yml
index caeb0a3f..86837e09 100644
--- a/.github/workflows/test-bitwuzla.yml
+++ b/.github/workflows/test-bitwuzla.yml
@@ -1,15 +1,12 @@
 name: Test Bitwuzla
 
 on:
-  push:
-    branches:
-      - main
   pull_request:
-    branches:
-      - main
+    types: [ labeled ]
 
 jobs:
   test-bitwuzla:
+    if: contains(github.event.pull_request.labels.*.name, 'bitwuzla')
     runs-on: ubuntu-latest
     env:
       OPAMCONFIRMLEVEL: unsafe-yes
diff --git a/.github/workflows/test-colibri2.yml b/.github/workflows/test-colibri2.yml
index e096604c..8c9a60fc 100644
--- a/.github/workflows/test-colibri2.yml
+++ b/.github/workflows/test-colibri2.yml
@@ -1,15 +1,12 @@
 name: Test Colibri2
 
 on:
-  push:
-    branches:
-      - main
   pull_request:
-    branches:
-      - main
+    types: [ labeled ]
 
 jobs:
   test-colibri2:
+    if: contains(github.event.pull_request.labels.*.name, 'colibri2')
     runs-on: ubuntu-latest
     env:
       OPAMCONFIRMLEVEL: unsafe-yes
diff --git a/.github/workflows/test-cvc5.yml b/.github/workflows/test-cvc5.yml
index b4781093..f9e151da 100644
--- a/.github/workflows/test-cvc5.yml
+++ b/.github/workflows/test-cvc5.yml
@@ -1,15 +1,12 @@
 name: Test cvc5
 
 on:
-  push:
-    branches:
-      - main
   pull_request:
-    branches:
-      - main
+    types: [ labeled ]
 
 jobs:
   test-cvc5:
+    if: contains(github.event.pull_request.labels.*.name, 'cvc5')
     runs-on: ubuntu-latest
     env:
       OPAMJOBS: 4