diff --git a/test-requirements.txt b/test-requirements.txt
index 82ec5172c2..e043171e8f 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -16,6 +16,7 @@ mpi4py
 # (where it's specified in setup.py)
 sqlalchemy>=1.4,<2
 sqlalchemy2-stubs
+sortedcontainers-stubs
 
 Sphinx==4.5.0
 twine