diff --git a/vessim/__init__.py b/vessim/__init__.py
index cb1d548c..a0313feb 100644
--- a/vessim/__init__.py
+++ b/vessim/__init__.py
@@ -53,7 +53,13 @@ def __init__(
         forecast: Optional[Union[pd.Series, pd.DataFrame]] = None,
     ):
         actual.sort_index()
-        self._actual = actual.to_frame() if isinstance(actual, pd.Series) else actual
+        if isinstance(actual, pd.Series):
+            self._actual = actual.to_frame()
+        elif isinstance(actual, pd.DataFrame):
+            self._actual = actual
+        else:
+            raise ValueError(f"Incompatible type {type(actual)} for 'actual'.")
+
         if isinstance(forecast, (pd.Series, pd.DataFrame)):
             forecast.sort_index()
             if isinstance(forecast, pd.Series):
diff --git a/vessim/cosim/consumer.py b/vessim/cosim/consumer.py
index 7adfc21e..ab893267 100644
--- a/vessim/cosim/consumer.py
+++ b/vessim/cosim/consumer.py
@@ -1,3 +1,5 @@
+from typing import Dict
+
 from vessim.core.consumer import Consumer
 from vessim.cosim._util import VessimSimulator, VessimModel
 
@@ -39,7 +41,7 @@ class _ComputingSystemModel(VessimModel):
     def __init__(self, consumer: Consumer):
         self.consumer = consumer
         self.p = 0.0
-        self.info = None
+        self.info: Dict = {}
 
     def step(self, time: int, inputs: dict) -> None:
         """Updates the power consumption of the system.