diff --git a/bayesflow/networks/summary_network.py b/bayesflow/networks/summary_network.py
index 06bb95ea8..2a10f6151 100644
--- a/bayesflow/networks/summary_network.py
+++ b/bayesflow/networks/summary_network.py
@@ -6,9 +6,8 @@
 
 
 class SummaryNetwork(keras.Layer):
-    def __init__(self, base_distribution: str = "normal", **kwargs):
+    def __init__(self, base_distribution: str = None, **kwargs):
         super().__init__(**keras_kwargs(kwargs))
-
         self.base_distribution = find_distribution(base_distribution)
 
     def build(self, input_shape):
diff --git a/bayesflow/utils/dispatch/find_distribution.py b/bayesflow/utils/dispatch/find_distribution.py
index 2e244c684..aa16d6d4f 100644
--- a/bayesflow/utils/dispatch/find_distribution.py
+++ b/bayesflow/utils/dispatch/find_distribution.py
@@ -13,6 +13,8 @@ def _(name: str, *args, **kwargs):
             from bayesflow.distributions import DiagonalNormal
 
             distribution = DiagonalNormal(*args, **kwargs)
+        case "none":
+            distribution = None
         case other:
             raise ValueError(f"Unsupported distribution name '{other}'.")
 
@@ -20,5 +22,5 @@ def _(name: str, *args, **kwargs):
 
 
 @find_distribution.register
-def _(constructor: type, *args, **kwargs):
-    return constructor(*args, **kwargs)
+def _(none: None, *args, **kwargs):
+    return None