diff --git a/distributed_shampoo/shampoo_types.py b/distributed_shampoo/shampoo_types.py
index 6d34f65..5ae7306 100644
--- a/distributed_shampoo/shampoo_types.py
+++ b/distributed_shampoo/shampoo_types.py
@@ -8,7 +8,7 @@
 """
 
 import enum
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 
 import torch
 
@@ -109,7 +109,9 @@ class ShampooPreconditionerConfig(PreconditionerConfig):
 
     """
 
-    amortized_computation_config: RootInvConfig = DefaultEigenConfig
+    amortized_computation_config: RootInvConfig = field(
+        default_factory=lambda: DefaultEigenConfig
+    )
 
 
 DefaultShampooConfig = ShampooPreconditionerConfig()
@@ -124,7 +126,9 @@ class EigenvalueCorrectedShampooPreconditionerConfig(PreconditionerConfig):
 
     """
 
-    amortized_computation_config: EigenvectorConfig = DefaultEighConfig
+    amortized_computation_config: EigenvectorConfig = field(
+        default_factory=lambda: DefaultEighConfig
+    )
 
 
 DefaultEigenvalueCorrectedShampooConfig = (