diff --git a/tests/test_requirements.txt b/tests/test_requirements.txt
index ce7f3a3f..6deaa039 100644
--- a/tests/test_requirements.txt
+++ b/tests/test_requirements.txt
@@ -1,5 +1,6 @@
 # the additional (!) requirements for testing the code
 # the dependencies of `quemb` itself are given in the setup.py
+mkl==2025.0.1
 block2 --extra-index-url=https://block-hczhai.github.io/block2-preview/pypi/
 git+https://github.com/pyscf/dmrgscf
 pytest