diff --git a/.github/workflows/pytest.yml b/.github/workflows/pytest.yml
index a4c27116..af98e210 100644
--- a/.github/workflows/pytest.yml
+++ b/.github/workflows/pytest.yml
@@ -43,4 +43,4 @@ jobs:
           uv pip freeze --system
 
       - name: Run tests
-        run: pytest --cov=pyerrors -vv
+        run: pytest --cov=pyerrors -vv -Werror
diff --git a/pyerrors/input/pandas.py b/pyerrors/input/pandas.py
index 13482983..af446cfc 100644
--- a/pyerrors/input/pandas.py
+++ b/pyerrors/input/pandas.py
@@ -1,6 +1,7 @@
 import warnings
 import gzip
 import sqlite3
+from contextlib import closing
 import pandas as pd
 from ..obs import Obs
 from ..correlators import Corr
@@ -29,9 +30,8 @@ def to_sql(df, table_name, db, if_exists='fail', gz=True, **kwargs):
     None
     """
     se_df = _serialize_df(df, gz=gz)
-    con = sqlite3.connect(db)
-    se_df.to_sql(table_name, con, if_exists=if_exists, index=False, **kwargs)
-    con.close()
+    with closing(sqlite3.connect(db)) as con:
+        se_df.to_sql(table_name, con=con, if_exists=if_exists, index=False, **kwargs)
 
 
 def read_sql(sql, db, auto_gamma=False, **kwargs):
@@ -52,9 +52,8 @@ def read_sql(sql, db, auto_gamma=False, **kwargs):
     data : pandas.DataFrame
         Dataframe with the content of the sqlite database.
     """
-    con = sqlite3.connect(db)
-    extract_df = pd.read_sql(sql, con, **kwargs)
-    con.close()
+    with closing(sqlite3.connect(db)) as con:
+        extract_df = pd.read_sql(sql, con=con, **kwargs)
     return _deserialize_df(extract_df, auto_gamma=auto_gamma)