diff --git a/bumble/avc.py b/bumble/avc.py
index 81502780..7e60d83a 100644
--- a/bumble/avc.py
+++ b/bumble/avc.py
@@ -134,6 +134,8 @@ class Frame:
                 opcode_offset = 3
         elif subunit_id == 6:
             raise core.InvalidPacketError("reserved subunit ID")
+        else:
+            raise core.InvalidPacketError("invalid subunit ID")
 
         opcode = Frame.OperationCode(data[opcode_offset])
         operands = data[opcode_offset + 1 :]
diff --git a/bumble/l2cap.py b/bumble/l2cap.py
index 53c84d5a..75e554c8 100644
--- a/bumble/l2cap.py
+++ b/bumble/l2cap.py
@@ -1911,6 +1911,7 @@ class ChannelManager:
             data = sum(1 << cid for cid in self.fixed_channels).to_bytes(8, 'little')
         else:
             result = L2CAP_Information_Response.NOT_SUPPORTED
+            data = b''
 
         self.send_control_frame(
             connection,
diff --git a/bumble/link.py b/bumble/link.py
index 8971e21b..9c7f4664 100644
--- a/bumble/link.py
+++ b/bumble/link.py
@@ -122,6 +122,8 @@ class LocalLink:
         elif transport == BT_BR_EDR_TRANSPORT:
             destination_controller = self.find_classic_controller(destination_address)
             source_address = sender_controller.public_address
+        else:
+            raise ValueError("unsupported transport type")
 
         if destination_controller is not None:
             destination_controller.on_link_acl_data(source_address, transport, data)
diff --git a/bumble/profiles/bap.py b/bumble/profiles/bap.py
index 8a00eafe..cd14bf19 100644
--- a/bumble/profiles/bap.py
+++ b/bumble/profiles/bap.py
@@ -350,6 +350,7 @@ class CodecSpecificCapabilities:
                 supported_max_codec_frames_per_sdu = value
 
         # It is expected here that if some fields are missing, an error should be raised.
+        # pylint: disable=possibly-used-before-assignment,used-before-assignment
         return CodecSpecificCapabilities(
             supported_sampling_frequencies=supported_sampling_frequencies,
             supported_frame_durations=supported_frame_durations,
@@ -426,6 +427,7 @@ class CodecSpecificConfiguration:
                 codec_frames_per_sdu = value
 
         # It is expected here that if some fields are missing, an error should be raised.
+        # pylint: disable=possibly-used-before-assignment,used-before-assignment
         return CodecSpecificConfiguration(
             sampling_frequency=sampling_frequency,
             frame_duration=frame_duration,
diff --git a/bumble/sdp.py b/bumble/sdp.py
index 88c575d2..90ac07c7 100644
--- a/bumble/sdp.py
+++ b/bumble/sdp.py
@@ -434,6 +434,8 @@ class DataElement:
             if size != 1:
                 raise InvalidArgumentError('boolean must be 1 byte')
             size_index = 0
+        else:
+            raise RuntimeError("internal error - self.type not supported")
 
         self.bytes = bytes([self.type << 3 | size_index]) + size_bytes + data
         return self.bytes
diff --git a/examples/run_extended_advertiser_2.py b/examples/run_extended_advertiser_2.py
index 735e1c5f..6f8d123a 100644
--- a/examples/run_extended_advertiser_2.py
+++ b/examples/run_extended_advertiser_2.py
@@ -64,6 +64,7 @@ async def main() -> None:
                 [(AdvertisingData.COMPLETE_LOCAL_NAME, "Bumble 2".encode("utf-8"))]
             )
 
+        # pylint: disable=possibly-used-before-assignment
         if device.host.number_of_supported_advertising_sets >= 2:
             set2 = await device.create_advertising_set(
                 random_address=Address("F0:F0:F0:F0:F0:F1"),
diff --git a/examples/run_hfp_handsfree.py b/examples/run_hfp_handsfree.py
index 5433284c..be1d1ba6 100644
--- a/examples/run_hfp_handsfree.py
+++ b/examples/run_hfp_handsfree.py
@@ -57,6 +57,9 @@ def on_dlc(dlc: rfcomm.DLC, configuration: hfp.HfConfiguration):
                 esco_parameters = hfp.ESCO_PARAMETERS[
                     hfp.DefaultCodecParameters.ESCO_CVSD_S4
                 ]
+            else:
+                raise RuntimeError("unknown active codec")
+
             connection.abort_on(
                 'disconnection',
                 connection.device.send_command(
diff --git a/pyproject.toml b/pyproject.toml
index eb22842c..8aa13c43 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -45,6 +45,7 @@ ignore="pandora" # FIXME: pylint does not support stubs yet:
 
 [tool.pylint.typecheck]
 signature-mutators="AsyncRunner.run_in_task"
+disable="not-callable"
 
 [tool.black]
 skip-string-normalization = true