diff --git a/CHANGELOG.md b/CHANGELOG.md
index 575ad00..2206300 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 CHANGELOG
 =========
 
+2024-09-26 (0.13.1)
+------------------
+- Bugfix for pydantic 2.x versions
+
 2024-09-26 (0.13.0)
 ------------------
 - Added configurable classical links.
diff --git a/squidasm/run/stack/config.py b/squidasm/run/stack/config.py
index 4a96efb..1f0f380 100644
--- a/squidasm/run/stack/config.py
+++ b/squidasm/run/stack/config.py
@@ -89,7 +89,7 @@ class CLinkConfig(YamlLoadable):
     """Name of the second stack being connected via clink."""
     typ: str
     """Type of the clink."""
-    cfg: Any
+    cfg: Optional[Any] = None
     """Configuration of the clink, allowed configuration depends on type."""
 
     @classmethod
@@ -109,7 +109,7 @@ class StackNetworkConfig(YamlLoadable):
     """List of all the stacks in the network."""
     links: List[LinkConfig]
     """List of all the links connecting the stacks in the network."""
-    clinks: Optional[List[CLinkConfig]]
+    clinks: Optional[List[CLinkConfig]] = None
     """List of all the links connecting the stacks in the network."""
 
     @classmethod