diff --git a/bumble/avdtp.py b/bumble/avdtp.py
index 85f7ede3..fd79dc33 100644
--- a/bumble/avdtp.py
+++ b/bumble/avdtp.py
@@ -580,10 +580,10 @@ def __init__(
         self.service_category = service_category
         self.service_capabilities_bytes = service_capabilities_bytes
 
-    def to_string(self, details: List[str] = []) -> str:
+    def to_string(self, details: Optional[List[str]] = None) -> str:
         attributes = ','.join(
             [name_or_number(AVDTP_SERVICE_CATEGORY_NAMES, self.service_category)]
-            + details
+            + (details or [])
         )
         return f'ServiceCapabilities({attributes})'
 
diff --git a/bumble/gatt.py b/bumble/gatt.py
index 3e679bbe..ea65116d 100644
--- a/bumble/gatt.py
+++ b/bumble/gatt.py
@@ -345,7 +345,7 @@ def __init__(
         uuid: Union[str, UUID],
         characteristics: List[Characteristic],
         primary=True,
-        included_services: List[Service] = [],
+        included_services: Iterable[Service] = (),
     ) -> None:
         # Convert the uuid to a UUID object if it isn't already
         if isinstance(uuid, str):
@@ -361,7 +361,7 @@ def __init__(
             uuid.to_pdu_bytes(),
         )
         self.uuid = uuid
-        self.included_services = included_services[:]
+        self.included_services = list(included_services)
         self.characteristics = characteristics[:]
         self.primary = primary
 
@@ -395,7 +395,7 @@ def __init__(
         self,
         characteristics: List[Characteristic],
         primary: bool = True,
-        included_services: List[Service] = [],
+        included_services: Iterable[Service] = (),
     ) -> None:
         super().__init__(self.UUID, characteristics, primary, included_services)