diff --git a/NodeGraphQt/base/graph.py b/NodeGraphQt/base/graph.py
index 5bed6341..c3231128 100644
--- a/NodeGraphQt/base/graph.py
+++ b/NodeGraphQt/base/graph.py
@@ -1727,8 +1727,12 @@ def _serialize(self, nodes):
         serial_data['graph']['pipe_style'] = self.pipe_style()
 
         # connection constrains.
-        serial_data['graph']['accept_connection_types'] = self.model.accept_connection_types
-        serial_data['graph']['reject_connection_types'] = self.model.reject_connection_types
+        serial_data['graph']['accept_connection_types'] = {
+            k: list(v) for k, v in self.model.accept_connection_types.items()
+        }
+        serial_data['graph']['reject_connection_types'] = {
+            k: list(v) for k, v in self.model.reject_connection_types.items()
+        }
 
         # serialize nodes.
         for n in nodes:
@@ -1798,9 +1802,13 @@ def _deserialize(self, data, relative_pos=False, pos=None):
 
             # connection constrains.
             elif attr_name == 'accept_connection_types':
-                self.model.accept_connection_types = attr_value
+                self.model.accept_connection_types = {
+                    k: set(v) for k, v in attr_value.items()
+                }
             elif attr_name == 'reject_connection_types':
-                self.model.reject_connection_types = attr_value
+                self.model.reject_connection_types = {
+                    k: set(v) for k, v in attr_value.items()
+                }
 
         # build the nodes.
         nodes = {}
diff --git a/NodeGraphQt/base/model.py b/NodeGraphQt/base/model.py
index 8d1e8a37..e5896324 100644
--- a/NodeGraphQt/base/model.py
+++ b/NodeGraphQt/base/model.py
@@ -245,7 +245,7 @@ def add_port_accept_connection_type(
     ):
         """
         Convenience function for adding to the "accept_connection_types" dict.
-        If the node graph model is unavailable yet then we store it to a
+        If the node graph model is unavailable, yet then we store it to a
         temp var that gets deleted.
 
         Args: