diff --git a/kfac_jax/_src/utils/accumulators.py b/kfac_jax/_src/utils/accumulators.py
index 259c076..fbbc20a 100644
--- a/kfac_jax/_src/utils/accumulators.py
+++ b/kfac_jax/_src/utils/accumulators.py
@@ -136,12 +136,12 @@ def __init__(
     self._multi_device = multi_device
 
   @property
-  def accumulator(self) -> TArrayTree:
+  def accumulator(self) -> TArrayTree | None:
     """The current value of the underlying not-normalized accumulator."""
     return self._accumulator
 
   @property
-  def weight(self) -> Numeric:
+  def weight(self) -> Numeric | None:
     """The current normalization weight of the underlying accumulator."""
     return self._weight
 
@@ -151,7 +151,7 @@ def multi_device(self) -> bool:
     return self._multi_device
 
   @property
-  def value(self) -> TArrayTree:
+  def value(self) -> TArrayTree | None:
     """The current normalized value of the accumulator."""
 
     if types.tree_is_empty(self.accumulator):
@@ -167,7 +167,7 @@ def clear(self) -> None:
     self._accumulator = None
     self._weight = None
 
-  def value_and_clear(self) -> TArrayTree:
+  def value_and_clear(self) -> TArrayTree | None:
     """Retrieves the normalized value of the accumulator and clears it."""
 
     value = self.value