diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 6020603..de49ebd 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -9,6 +9,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          - { python: "3.13", os: ubuntu-latest, env: py313-3 }
           - { python: "3.12", os: ubuntu-latest, env: py312-3 }
           - { python: "3.11", os: ubuntu-latest, env: py311-3 }
           - { python: "3.11", os: ubuntu-latest, env: py311-2 }
diff --git a/pyproject.toml b/pyproject.toml
index 635e736..178e4f5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,8 +21,9 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
 ]
-dependencies = ["flask>=2.0", "MarkupSafe>=2.0.0", "python-liquid>=1.1.0"]
+dependencies = ["flask>=2.0", "MarkupSafe>=2.0.0, <3", "python-liquid>=1.1.0"]
 
 [project.urls]
 "Change Log" = "https://github.com/jg-rp/flask-liquid/blob/main/CHANGES.md"
@@ -63,7 +64,7 @@ lint = "ruff check ."
 typing = "mypy"
 
 [[tool.hatch.envs.test.matrix]]
-python = ["38", "39", "310", "311", "312", "pypy38", "pypy39", "pypy310"]
+python = ["38", "39", "310", "311", "312", "313", "pypy38", "pypy39", "pypy310"]
 flask = ["2", "3"]
 
 [tool.hatch.envs.test.overrides]