diff --git a/.github/workflows/examples.yml b/.github/workflows/examples.yml
index e802f0b0..473e77d0 100644
--- a/.github/workflows/examples.yml
+++ b/.github/workflows/examples.yml
@@ -36,6 +36,7 @@ jobs:
           pip install .
           pip install pytest
           pip install nbmake
+          pip install -U matplotlib!=3.7.0 # Exclude version 3.7.0 of matplotlib as this breaks local imports of style files.
 
       - name: Run tests
         run: pytest -vv --nbmake examples/*.ipynb
diff --git a/pyerrors/correlators.py b/pyerrors/correlators.py
index a655d36b..67533cb2 100644
--- a/pyerrors/correlators.py
+++ b/pyerrors/correlators.py
@@ -23,6 +23,8 @@ class Corr:
 
     """
 
+    __slots__ = ["content", "N", "T", "tag", "prange"]
+
     def __init__(self, data_input, padding=[0, 0], prange=None):
         """ Initialize a Corr object.