diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1aa2e48..ad7192f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -98,6 +98,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
+      max-parallel: 1
       matrix:
         os: [macos-15-intel, macos-latest, windows-latest, ubuntu-latest]
         python-version: ["3.9", "3.10", "3.11"]
diff --git a/requirements.txt b/requirements.txt
index bebcdc1..513c4c3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,7 @@
 # Dependencies required for installation (keep in sync with setup.py)
 requests>=2.16.2
 six >= 1.12.0
-stone>=2,<3.3.3
+stone>=2,<3.3.9
 # Other dependencies for development
 ply
 pytest
diff --git a/setup.py b/setup.py
index 6c11c3d..133719f 100644
--- a/setup.py
+++ b/setup.py
@@ -27,7 +27,7 @@
 install_reqs = [
     'requests>=2.16.2',
     'six >= 1.12.0',
-    'stone>=2,<3.3.3',
+    'stone>=2,<3.3.9',
 ]
 
 setup_requires = [
diff --git a/test/requirements.txt b/test/requirements.txt
index 9f263bd..8328a1c 100644
--- a/test/requirements.txt
+++ b/test/requirements.txt
@@ -2,4 +2,4 @@ pytest
 mock
 pytest-mock
 coverage
-stone>=2,<3.3.3
+stone>=2,<3.3.9