diff --git a/.buildconfig/ci-linux.yml b/.buildconfig/ci-linux.yml
index 9e987335f..65e815b54 100644
--- a/.buildconfig/ci-linux.yml
+++ b/.buildconfig/ci-linux.yml
@@ -47,3 +47,6 @@ dependencies:
 
   # docs and tests
   - sciline==24.10.0
+
+  # Temporary pin, see https://github.com/mantidproject/mantid/issues/39393
+  - muparser==2.3.4