diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 15a2763..c6d69ed 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -60,7 +60,11 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         python: ['3.10']
-        spawn_backend: ['trio', 'mp']
+        spawn_backend: [
+          'trio',
+          'mp_spawn',
+          'mp_forkserver',
+        ]
 
     steps: