diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index df8a6d85..45387941 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,6 +1,7 @@
 Changelog
 =========
 
+- Restrict matplotlib version < 3.9 for compatibility with GPy
 - Add option to use additive or multiplicative adjustment in any acquisition method
 - Add `arziv`-mocking to rtd-setup
 - Add convenience method for obtaining elfi samples as `InferenceData`` to be used with `arviz`
diff --git a/requirements.txt b/requirements.txt
index 8903535c..1f086fdf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,7 @@
 dask[distributed]>=2.30.0
 numpy>=1.12.1
 scipy>=0.19
-matplotlib>=1.1
+matplotlib>=1.1,<3.9
 GPy>=1.0.9
 networkX>=2.0
 ipyparallel>=6
@@ -9,4 +9,4 @@ toolz>=0.8
 scikit-learn>=0.18.1
 numdifftools>=0.9
 arviz>=0.12.1
-setuptools>=69
\ No newline at end of file
+setuptools>=69