diff --git a/CHANGELOG.md b/CHANGELOG.md
index 87cbbab5..b1b8ee33 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@ The changelog format is based on [Keep a Changelog](https://keepachangelog.com/e
 * updated to sphinx-argparse-cli>=1.15  (from sphinx-argparse-cli>=1.11)
 * updated to myst-parser>=3.0  (from myst-parser>=2.0)
 * updated to furo>=2024.4  (from furo>=2023.9.10)
+* updated to matplotlib>=3.9  (from matplotlib>=3.8)
 
 ### Changed
 * replaced black formatter with ruff formatter
diff --git a/pyproject.toml b/pyproject.toml
index cfc4d75e..8cf27562 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,7 +37,7 @@ dependencies = [
     "lxml>=5.2",
     "numpy>=1.26,<2.0",
     "pandas>=2.2",
-    "matplotlib>=3.8",
+    "matplotlib>=3.9",
     "graphviz>=0.20",
     "dictIO>=0.3.3",
 ]
diff --git a/requirements.txt b/requirements.txt
index c24c8dd2..64229d8d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,7 @@
 lxml>=5.2
 numpy>=1.26,<2.0
 pandas>=2.2
-matplotlib>=3.8
+matplotlib>=3.9
 graphviz>=0.20
 
 dictIO>=0.3.3