diff --git a/ecl2df/common.py b/ecl2df/common.py
index fcfb4925f..c9aef1e18 100644
--- a/ecl2df/common.py
+++ b/ecl2df/common.py
@@ -627,8 +627,8 @@ def df2ecl(
 def generic_ecltable(
     dframe: pd.DataFrame,
     keyword: str,
-    comment: str = None,
-    renamer: Dict[str, str] = None,
+    comment: Optional[str] = None,
+    renamer: Optional[Dict[str, str]] = None,
     drop_trailing_columns: bool = True,
 ) -> str:
     """Construct a typical Eclipse table for data following
diff --git a/setup.py b/setup.py
index 12ce4b765..09e1041e7 100644
--- a/setup.py
+++ b/setup.py
@@ -19,7 +19,7 @@
     "ecl",
     "numpy",
     "opm>=2020.10.2",  # NB: Pypi versions.
-    "pandas",
+    "pandas<2.0",
     "pyarrow",
     "pyyaml>=5.1",
     "treelib",