diff --git a/ml_mdm/diffusion.py b/ml_mdm/diffusion.py
index 22d55f2..c11b034 100644
--- a/ml_mdm/diffusion.py
+++ b/ml_mdm/diffusion.py
@@ -29,7 +29,7 @@ def sv(x, f):
 @dataclass
 class DiffusionConfig:
     sampler_config: samplers.SamplerConfig = field(
-        default=samplers.SamplerConfig(), metadata={"help": "Sampler configuration"}
+        default_factory=samplers.SamplerConfig, metadata={"help": "Sampler configuration"}
     )
     model_output_scale: float = field(
         default=0,
diff --git a/ml_mdm/models/nested_unet.py b/ml_mdm/models/nested_unet.py
index 43a4abb..b87c20c 100644
--- a/ml_mdm/models/nested_unet.py
+++ b/ml_mdm/models/nested_unet.py
@@ -22,7 +22,7 @@
 @dataclass
 class NestedUNetConfig(UNetConfig):
     inner_config: UNetConfig = field(
-        default=UNetConfig(nesting=True),
+        default_factory=lambda: UNetConfig(nesting=True),
         metadata={"help": "inner unet used as middle blocks"},
     )
     skip_mid_blocks: bool = field(default=True)
@@ -55,7 +55,7 @@ class NestedUNetConfig(UNetConfig):
 @dataclass
 class Nested2UNetConfig(NestedUNetConfig):
     inner_config: NestedUNetConfig = field(
-        default=NestedUNetConfig(nesting=True, initialize_inner_with_pretrained=None)
+        default_factory=lambda: NestedUNetConfig(nesting=True, initialize_inner_with_pretrained=None)
     )
 
 
@@ -63,7 +63,7 @@ class Nested2UNetConfig(NestedUNetConfig):
 @dataclass
 class Nested3UNetConfig(Nested2UNetConfig):
     inner_config: Nested2UNetConfig = field(
-        default=Nested2UNetConfig(nesting=True, initialize_inner_with_pretrained=None)
+        default_factory=lambda: Nested2UNetConfig(nesting=True, initialize_inner_with_pretrained=None)
     )
 
 
@@ -71,7 +71,7 @@ class Nested3UNetConfig(Nested2UNetConfig):
 @dataclass
 class Nested4UNetConfig(Nested3UNetConfig):
     inner_config: Nested3UNetConfig = field(
-        default=Nested3UNetConfig(nesting=True, initialize_inner_with_pretrained=None)
+        default_factory=lambda: Nested3UNetConfig(nesting=True, initialize_inner_with_pretrained=None)
     )
 
 
@@ -96,7 +96,7 @@ def download(vision_model_path):
 @config.register_model("nested_unet")
 class NestedUNet(UNet):
     def __init__(self, input_channels, output_channels, config: NestedUNetConfig):
-        super().__init__(input_channels, output_channels, config)
+        super().__init__(input_channels, output_channels=output_channels, config=config)
         config.inner_config.conditioning_feature_dim = config.conditioning_feature_dim
         if getattr(config.inner_config, "inner_config", None) is None:
             self.inner_unet = UNet(input_channels, output_channels, config.inner_config)
diff --git a/ml_mdm/models/unet.py b/ml_mdm/models/unet.py
index 94b7d60..43a8506 100644
--- a/ml_mdm/models/unet.py
+++ b/ml_mdm/models/unet.py
@@ -115,7 +115,7 @@ class UNetConfig:
     temporal_spatial_ds: bool = field(default=False)
     temporal_positional_encoding: bool = field(default=False)
     resnet_config: ResNetConfig = field(
-        default=ResNetConfig(), metadata={"help": "Resnet configs"}
+        default_factory=ResNetConfig, metadata={"help": "Resnet configs"}
     )
 
     def __post_init__(self):