diff --git a/.github/workflows/CI.yaml b/.github/workflows/CI.yaml
index 3149376..7142faf 100644
--- a/.github/workflows/CI.yaml
+++ b/.github/workflows/CI.yaml
@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ['3.10', '3.11', '3.12', '3.13']
+        python-version: ['3.9', '3.10', '3.11', '3.12']
 
     steps:
       - uses: actions/checkout@v4
diff --git a/docs/changelog.md b/docs/changelog.md
index c7dae6f..ae1920c 100644
--- a/docs/changelog.md
+++ b/docs/changelog.md
@@ -2,14 +2,6 @@
 
 ## 0.1.2 - 2025-02-10
 
-### Added
-
-- Support for Python 3.13.
-
-### Removed
-
-- Support for Python 3.9.
-
 ### Fixed
 
 - Added new type hints.
diff --git a/pyproject.toml b/pyproject.toml
index 7fd34c1..c073b5b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,9 +18,10 @@ classifiers = [
     "License :: OSI Approved :: MIT License",
     "Programming Language :: Python :: 3",
 ]
-requires-python = ">=3.10"
+requires-python = ">=3.8"
 # Declare any run-time dependencies that should be installed with the package.
 dependencies = [
+    "importlib-resources;python_version<'3.10'",
     "numpy>=1.20.0",
     "scipy>=1.6.0",
     "matplotlib>=3.3.0",