diff --git a/changelog.d/554.changed.md b/changelog.d/554.changed.md
new file mode 100644
index 00000000..d861101f
--- /dev/null
+++ b/changelog.d/554.changed.md
@@ -0,0 +1 @@
+Allow downstream packages to use pytest 9 while retaining pytest 8 compatibility.
diff --git a/pyproject.toml b/pyproject.toml
index 0d302fc7..cbe0acb2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ dependencies = [
     "pandas>=1",
     "plotly>=5,<6",
     "psutil>=6,<7",
-    "pytest>=8,<9",
+    "pytest>=8,<10",
     "pyvis>=0.3.2",
     "requests>=2,<3",
     "sortedcontainers<3",
diff --git a/uv.lock b/uv.lock
index 28d0a9f4..2608e850 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1364,7 +1364,7 @@ wheels = [
 
 [[package]]
 name = "policyengine-core"
-version = "3.31.1"
+version = "3.32.9"
 source = { editable = "." }
 dependencies = [
     { name = "dpath" },
@@ -1424,7 +1424,7 @@ requires-dist = [
     { name = "pandas", specifier = ">=1" },
     { name = "plotly", specifier = ">=5,<6" },
     { name = "psutil", specifier = ">=6,<7" },
-    { name = "pytest", specifier = ">=8,<9" },
+    { name = "pytest", specifier = ">=8,<10" },
     { name = "pytest-cov", marker = "extra == 'dev'" },
     { name = "pytest-rerunfailures", marker = "extra == 'dev'", specifier = ">=10,<15" },
     { name = "pyvis", specifier = ">=0.3.2" },
@@ -1563,7 +1563,7 @@ wheels = [
 
 [[package]]
 name = "pytest"
-version = "8.4.2"
+version = "9.1.1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
     { name = "colorama", marker = "sys_platform == 'win32'" },
@@ -1572,9 +1572,9 @@ dependencies = [
     { name = "pluggy" },
     { name = "pygments" },
 ]
-sdist = { url = "https://files.pythonhosted.org/packages/a3/5c/00a0e072241553e1a7496d638deababa67c5058571567b92a7eaa258397c/pytest-8.4.2.tar.gz", hash = "sha256:86c0d0b93306b961d58d62a4db4879f27fe25513d4b969df351abdddb3c30e01", size = 1519618, upload-time = "2025-09-04T14:34:22.711Z" }
+sdist = { url = "https://files.pythonhosted.org/packages/e4/47/b9efed96c114afcfa3c9d3fe98a76a1d14c74a9e266d397cf6eb64be5e01/pytest-9.1.1.tar.gz", hash = "sha256:1088fbde8f2b49d95a549a195707afa7a76a3ce9bcadc26b6d71f0ffda5fe313", size = 1636369, upload-time = "2026-06-19T10:58:32.857Z" }
 wheels = [
-    { url = "https://files.pythonhosted.org/packages/a8/a4/20da314d277121d6534b3a980b29035dcd51e6744bd79075a6ce8fa4eb8d/pytest-8.4.2-py3-none-any.whl", hash = "sha256:872f880de3fc3a5bdc88a11b39c9710c3497a547cfa9320bc3c5e62fbf272e79", size = 365750, upload-time = "2025-09-04T14:34:20.226Z" },
+    { url = "https://files.pythonhosted.org/packages/24/25/1de2678b631f5a49215c6c96fff41ba892b0a34df68d6d80292b1b48aa7f/pytest-9.1.1-py3-none-any.whl", hash = "sha256:37a86b45efb9a47a61a36449063e8e18d0cab3161329fc099eb21783169c4f0c", size = 386536, upload-time = "2026-06-19T10:58:31.347Z" },
 ]
 
 [[package]]