diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index d89c5ca..66feadb 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -59,43 +59,43 @@ jobs:
             free_threaded_support: True
 
           # MacOS x86_64
-          - os: macos-13
+          - os: macos-15-intel
             python: 39
             platform_id: macosx_x86_64
-          - os: macos-13
+          - os: macos-15-intel
             python: 310
             platform_id: macosx_x86_64
-          - os: macos-13
+          - os: macos-15-intel
             python: 311
             platform_id: macosx_x86_64
-          - os: macos-13
+          - os: macos-15-intel
             python: 312
             platform_id: macosx_x86_64
-          - os: macos-13
+          - os: macos-15-intel
             python: 313
             platform_id: macosx_x86_64
-          - os: macos-13
+          - os: macos-15-intel
             python: 313t
             platform_id: macosx_x86_64
             free_threaded_support: True
 
           # MacOS arm64
-          - os: macos-14
+          - os: macos-latest
             python: 39
             platform_id: macosx_arm64
-          - os: macos-14
+          - os: macos-latest
             python: 310
             platform_id: macosx_arm64
-          - os: macos-14
+          - os: macos-latest
             python: 311
             platform_id: macosx_arm64
-          - os: macos-14
+          - os: macos-latest
             python: 312
             platform_id: macosx_arm64
-          - os: macos-14
+          - os: macos-latest
             python: 313
             platform_id: macosx_arm64
-          - os: macos-14
+          - os: macos-latest
             python: 313t
             platform_id: macosx_arm64
             free_threaded_support: True
@@ -124,7 +124,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Build sdist
-        run: pipx run build --sdist
+        run: USE_CYTHON=1 pipx run build --sdist
 
       - uses: actions/upload-artifact@v4
         with:
diff --git a/MANIFEST.in b/MANIFEST.in
index 2c1e001..00b37fe 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,2 +1,5 @@
 include src/stochastic_arrow/obsidian.h
-include src/stochastic_arrow/mersenne.h
\ No newline at end of file
+include src/stochastic_arrow/mersenne.h
+include src/stochastic_arrow/arrow.pxd
+include src/stochastic_arrow/arrowhead.pyx
+include src/stochastic_arrow/obsidian.pxd
\ No newline at end of file
diff --git a/README.md b/README.md
index 1cdd3eb..595fc0b 100644
--- a/README.md
+++ b/README.md
@@ -133,6 +133,9 @@ More examples:
 
 ## Changelog
 
+### Version 1.1.1
+* Include files to install source dist without `USE_CYTHON=1`.
+
 ### Version 1.1.0
 * Update build toolchain and automatically build/publish wheels for all
 major platforms and recent Python versions.
diff --git a/pyproject.toml b/pyproject.toml
index c34e725..efa310c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,3 @@
 [build-system]
-requires = ["setuptools", "wheel", "cython==3.1.0a1; python_version=='3.13'", "cython; python_version!='3.13'", "numpy"]
+requires = ["setuptools", "wheel", "cython", "numpy"]
 build-backend = "setuptools.build_meta"