diff --git a/etc/requirements.pip.txt b/etc/requirements.pip.txt
index 9615b9a8..5a76755b 100644
--- a/etc/requirements.pip.txt
+++ b/etc/requirements.pip.txt
@@ -3,7 +3,7 @@ pytest-xdist
 appdirs
 requests
 numpy
-matplotlib
+matplotlib<=3.9.4
 bmipy
 affine
 scipy