diff --git a/tests/handlers/filesystem/test_jffs2.py b/tests/handlers/filesystem/test_jffs2.py
index 64c913a99a..9b2f910e69 100644
--- a/tests/handlers/filesystem/test_jffs2.py
+++ b/tests/handlers/filesystem/test_jffs2.py
@@ -1,7 +1,6 @@
 import binascii
 
 import pytest
-from dissect.cstruct import Instance
 from helpers import unhex
 
 from unblob.file_utils import Endian, File
@@ -59,7 +58,7 @@ def get_valid_jffs2_old_be_header():
     )
 
 
-def calculate_crc(header: Instance):
+def calculate_crc(header):
     return (binascii.crc32(header.dumps()[:-4], -1) ^ -1) & 0xFFFFFFFF
 
 
@@ -188,9 +187,7 @@ def calculate_crc(header: Instance):
         ),
     ],
 )
-def test_valid_header_new(
-    header: Instance, node_start_offset: int, eof: int, expected: bool
-):
+def test_valid_header_new(header, node_start_offset: int, eof: int, expected: bool):
     header.hdr_crc = calculate_crc(header)
     assert new_handler.valid_header(header, node_start_offset, eof) == expected
 
@@ -270,9 +267,7 @@ def test_valid_header_new(
         ),
     ],
 )
-def test_valid_header_old(
-    header: Instance, node_start_offset: int, eof: int, expected: bool
-):
+def test_valid_header_old(header, node_start_offset: int, eof: int, expected: bool):
     header.hdr_crc = calculate_crc(header)
     assert old_handler.valid_header(header, node_start_offset, eof) == expected
 
diff --git a/unblob/file_utils.py b/unblob/file_utils.py
index e532be6ab5..e476b552ba 100644
--- a/unblob/file_utils.py
+++ b/unblob/file_utils.py
@@ -12,7 +12,7 @@
 from pathlib import Path
 from typing import Iterable, Iterator, List, Literal, Optional, Tuple, Union
 
-from dissect.cstruct import Instance, cstruct
+from dissect.cstruct import cstruct
 from structlog import get_logger
 
 from .logging import format_hex
@@ -336,7 +336,7 @@ def parse(
         struct_name: str,
         file: Union[File, bytes],
         endian: Endian,
-    ) -> Instance:
+    ):
         cparser = self.cparser_le if endian is Endian.LITTLE else self.cparser_be
         struct_parser = getattr(cparser, struct_name)
         return struct_parser(file)
diff --git a/unblob/handlers/archive/arc.py b/unblob/handlers/archive/arc.py
index 86c3a076d9..5d5545eb16 100644
--- a/unblob/handlers/archive/arc.py
+++ b/unblob/handlers/archive/arc.py
@@ -1,6 +1,5 @@
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.extractors.command import Command
@@ -54,7 +53,7 @@ def valid_name(self, name: bytes) -> bool:
         except UnicodeDecodeError:
             return False
 
-    def valid_header(self, header: Instance) -> bool:
+    def valid_header(self, header) -> bool:
         if header.archive_marker != 0x1A:
             return False
         if header.header_type > 0x07:
diff --git a/unblob/handlers/archive/cpio.py b/unblob/handlers/archive/cpio.py
index 52c743eb32..adc997fc37 100644
--- a/unblob/handlers/archive/cpio.py
+++ b/unblob/handlers/archive/cpio.py
@@ -5,7 +5,6 @@
 from typing import Optional, Type
 
 import attr
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from ...file_utils import (
@@ -252,7 +251,7 @@ def _pad_file(self, end_offset: int) -> int:
         return end_offset
 
     @classmethod
-    def _pad_header(cls, header: Instance, c_namesize: int) -> int:
+    def _pad_header(cls, header, c_namesize: int) -> int:
         return round_up(len(header) + c_namesize, cls._PAD_ALIGN)
 
     @classmethod
diff --git a/unblob/handlers/archive/dlink/encrpted_img.py b/unblob/handlers/archive/dlink/encrpted_img.py
index 28ffb0108d..1ae6ae95f8 100644
--- a/unblob/handlers/archive/dlink/encrpted_img.py
+++ b/unblob/handlers/archive/dlink/encrpted_img.py
@@ -3,7 +3,6 @@
 from typing import Optional
 
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.file_utils import File, InvalidInputFormat
@@ -53,7 +52,7 @@ class EncrptedHandler(StructHandler):
     HEADER_STRUCT = "dlink_header_t"
     EXTRACTOR = EncrptedExtractor()
 
-    def is_valid_header(self, header: Instance) -> bool:
+    def is_valid_header(self, header) -> bool:
         if header.size < len(header):
             return False
         return True
diff --git a/unblob/handlers/archive/dlink/shrs.py b/unblob/handlers/archive/dlink/shrs.py
index 63bd9d9313..7601871bb9 100644
--- a/unblob/handlers/archive/dlink/shrs.py
+++ b/unblob/handlers/archive/dlink/shrs.py
@@ -4,7 +4,6 @@
 from typing import Optional
 
 from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.file_utils import File, InvalidInputFormat
@@ -70,7 +69,7 @@ class SHRSHandler(StructHandler):
     HEADER_STRUCT = "dlink_header_t"
     EXTRACTOR = SHRSExtractor()
 
-    def is_valid_header(self, header: Instance, file: File) -> bool:
+    def is_valid_header(self, header, file: File) -> bool:
         if header.file_size < len(header):
             return False
         # we're exactly past the header, we compute the digest
diff --git a/unblob/handlers/archive/engeniustech/engenius.py b/unblob/handlers/archive/engeniustech/engenius.py
index d403605bdc..a12f11fe1a 100644
--- a/unblob/handlers/archive/engeniustech/engenius.py
+++ b/unblob/handlers/archive/engeniustech/engenius.py
@@ -1,7 +1,6 @@
 from pathlib import Path
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.file_utils import Endian, File, InvalidInputFormat, StructParser
@@ -81,7 +80,7 @@ class EngeniusHandler(StructHandler):
     EXTRACTOR = EngeniusExtractor()
     PATTERN_MATCH_OFFSET = -0x5C
 
-    def is_valid_header(self, header: Instance) -> bool:
+    def is_valid_header(self, header) -> bool:
         if header.length <= len(header):
             return False
         try:
diff --git a/unblob/handlers/archive/hp/bdl.py b/unblob/handlers/archive/hp/bdl.py
index abac452ce1..48a0129da4 100644
--- a/unblob/handlers/archive/hp/bdl.py
+++ b/unblob/handlers/archive/hp/bdl.py
@@ -2,7 +2,6 @@
 from pathlib import Path
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.extractor import carve_chunk_to_file
@@ -35,7 +34,7 @@
 """
 
 
-def is_valid_header(header: Instance) -> bool:
+def is_valid_header(header) -> bool:
     if header.toc_offset == 0 or header.toc_entries == 0:
         return False
     try:
diff --git a/unblob/handlers/archive/hp/ipkg.py b/unblob/handlers/archive/hp/ipkg.py
index c7503bec76..55c65c6f18 100644
--- a/unblob/handlers/archive/hp/ipkg.py
+++ b/unblob/handlers/archive/hp/ipkg.py
@@ -2,7 +2,6 @@
 from pathlib import Path
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.file_utils import (
@@ -48,7 +47,7 @@
 """
 
 
-def is_valid_header(header: Instance) -> bool:
+def is_valid_header(header) -> bool:
     if header.toc_offset == 0 or header.toc_entries == 0:
         return False
     try:
diff --git a/unblob/handlers/archive/instar/bneg.py b/unblob/handlers/archive/instar/bneg.py
index 101cb25c9b..ec526df2ea 100644
--- a/unblob/handlers/archive/instar/bneg.py
+++ b/unblob/handlers/archive/instar/bneg.py
@@ -1,7 +1,6 @@
 from pathlib import Path
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.extractor import carve_chunk_to_file
@@ -70,7 +69,7 @@ class BNEGHandler(StructHandler):
     HEADER_STRUCT = "bneg_header_t"
     EXTRACTOR = BNEGExtractor()
 
-    def is_valid_header(self, header: Instance) -> bool:
+    def is_valid_header(self, header) -> bool:
         if header.partition_1_size == 0:
             return False
         if header.partition_2_size == 0:
diff --git a/unblob/handlers/archive/netgear/chk.py b/unblob/handlers/archive/netgear/chk.py
index 441906359c..f6c023b68c 100644
--- a/unblob/handlers/archive/netgear/chk.py
+++ b/unblob/handlers/archive/netgear/chk.py
@@ -2,7 +2,6 @@
 from pathlib import Path
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.extractor import carve_chunk_to_file
@@ -59,7 +58,7 @@ class NetgearCHKHandler(StructHandler):
     HEADER_STRUCT = "chk_header_t"
     EXTRACTOR = CHKExtractor()
 
-    def is_valid_header(self, header: Instance) -> bool:
+    def is_valid_header(self, header) -> bool:
         if header.header_len != len(header):
             return False
         try:
diff --git a/unblob/handlers/archive/netgear/trx.py b/unblob/handlers/archive/netgear/trx.py
index 9fdb180807..dfbff917eb 100644
--- a/unblob/handlers/archive/netgear/trx.py
+++ b/unblob/handlers/archive/netgear/trx.py
@@ -3,7 +3,6 @@
 from pathlib import Path
 from typing import Iterable, Optional, cast
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.extractor import carve_chunk_to_file
@@ -75,12 +74,12 @@ def calculate_chunk(self, file: File, start_offset: int) -> Optional[ValidChunk]
             start_offset=start_offset, end_offset=start_offset + header.len
         )
 
-    def is_valid_header(self, header: Instance) -> bool:
+    def is_valid_header(self, header) -> bool:
         if header.len < len(header):
             return False
         return True
 
-    def _is_crc_valid(self, file: File, start_offset: int, header: Instance) -> bool:
+    def _is_crc_valid(self, file: File, start_offset: int, header) -> bool:
         file.seek(start_offset + CRC_CONTENT_OFFSET)
         content = bytearray(file.read(header.len - CRC_CONTENT_OFFSET))
         computed_crc = (binascii.crc32(content) ^ -1) & 0xFFFFFFFF
diff --git a/unblob/handlers/archive/qnap/qnap_nas.py b/unblob/handlers/archive/qnap/qnap_nas.py
index 6728c55f1b..fdadfef0b5 100644
--- a/unblob/handlers/archive/qnap/qnap_nas.py
+++ b/unblob/handlers/archive/qnap/qnap_nas.py
@@ -3,7 +3,6 @@
 from typing import Optional
 
 import attr
-from dissect.cstruct import Instance
 from pyperscan import Flag, Pattern, Scan, StreamDatabase
 from structlog import get_logger
 
@@ -44,7 +43,7 @@ class QTSSearchContext:
     end_offset: int
 
 
-def is_valid_header(header: Instance) -> bool:
+def is_valid_header(header) -> bool:
     try:
         header.device_id.decode("utf-8")
         header.file_version.decode("utf-8")
diff --git a/unblob/handlers/archive/xiaomi/hdr.py b/unblob/handlers/archive/xiaomi/hdr.py
index 47beae8ace..30d3a659ae 100644
--- a/unblob/handlers/archive/xiaomi/hdr.py
+++ b/unblob/handlers/archive/xiaomi/hdr.py
@@ -3,7 +3,6 @@
 from pathlib import Path
 from typing import Iterable, Optional, Tuple, cast
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.file_utils import (
@@ -74,7 +73,7 @@ def calculate_crc(file: File, start_offset: int, size: int) -> int:
     return (digest ^ -1) & 0xFFFFFFFF
 
 
-def is_valid_blob_header(blob_header: Instance) -> bool:
+def is_valid_blob_header(blob_header) -> bool:
     if blob_header.magic == BLOB_MAGIC:
         return False
     if not blob_header.size:
@@ -86,7 +85,7 @@ def is_valid_blob_header(blob_header: Instance) -> bool:
     return True
 
 
-def is_valid_header(header: Instance) -> bool:
+def is_valid_header(header) -> bool:
     if header.signature_offset < len(header):
         return False
     if not header.blob_offsets[0]:
@@ -147,7 +146,7 @@ def calculate_chunk(self, file: File, start_offset: int) -> Optional[ValidChunk]
         return ValidChunk(start_offset=start_offset, end_offset=end_offset)
 
     def _is_crc_valid(
-        self, file: File, header: Instance, start_offset: int, end_offset: int
+        self, file: File, header, start_offset: int, end_offset: int
     ) -> bool:
         computed_crc = calculate_crc(
             file,
diff --git a/unblob/handlers/archive/zip.py b/unblob/handlers/archive/zip.py
index 53db5307fc..0a63ec09fb 100644
--- a/unblob/handlers/archive/zip.py
+++ b/unblob/handlers/archive/zip.py
@@ -2,7 +2,6 @@
 import struct
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from ...extractors import Command
@@ -90,7 +89,7 @@ def has_encrypted_files(
         self,
         file: File,
         start_offset: int,
-        end_of_central_directory: Instance,
+        end_of_central_directory,
     ) -> bool:
         file.seek(start_offset + end_of_central_directory.offset_of_cd, io.SEEK_SET)
         for _ in range(end_of_central_directory.total_entries):
@@ -104,7 +103,7 @@ def has_encrypted_files(
         return False
 
     @staticmethod
-    def is_zip64_eocd(end_of_central_directory: Instance):
+    def is_zip64_eocd(end_of_central_directory):
         # see https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.1.TXT section J
         return (
             end_of_central_directory.disk_number == 0xFFFF
@@ -116,14 +115,14 @@ def is_zip64_eocd(end_of_central_directory: Instance):
         )
 
     @staticmethod
-    def is_zip64_cd_file(file_header: Instance):
+    def is_zip64_cd_file(file_header):
         # see https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT section 4.3.9.2
         return (
             file_header.file_size == 0xFFFFFFFF
             or file_header.compress_size == 0xFFFFFFFF
         )
 
-    def _parse_zip64(self, file: File, start_offset: int, offset: int) -> Instance:
+    def _parse_zip64(self, file: File, start_offset: int, offset: int):
         file.seek(start_offset, io.SEEK_SET)
         for eocd_locator_offset in iterate_patterns(
             file, struct.pack("<I", self.ZIP64_EOCD_LOCATOR_HEADER)
diff --git a/unblob/handlers/executable/elf.py b/unblob/handlers/executable/elf.py
index 81ef24b502..8ab2d86fb5 100644
--- a/unblob/handlers/executable/elf.py
+++ b/unblob/handlers/executable/elf.py
@@ -5,7 +5,6 @@
 
 import attr
 import lief
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.extractor import carve_chunk_to_file
@@ -138,7 +137,7 @@ class _ELFBase(StructHandler):
     SECTION_HEADER_STRUCT = "elf_shdr_t"
     PROGRAM_HEADER_STRUCT = "elf_phdr_t"
 
-    def is_valid_header(self, header: Instance) -> bool:
+    def is_valid_header(self, header) -> bool:
         # check that header fields have valid values
         try:
             lief.ELF.E_TYPE(header.e_type)
@@ -197,9 +196,7 @@ def get_last_program_end(
 
         return last_program_end
 
-    def get_end_offset(
-        self, file: File, start_offset: int, header: Instance, endian
-    ) -> int:
+    def get_end_offset(self, file: File, start_offset: int, header, endian) -> int:
         # Usually the section header is the last, but in some cases the program headers are
         # put to the end of the file, and in some cases sections header and actual sections
         # can be also intermixed, so we need also to check the end of the last section and
diff --git a/unblob/handlers/filesystem/cramfs.py b/unblob/handlers/filesystem/cramfs.py
index 66c78c660d..c04bc9e020 100644
--- a/unblob/handlers/filesystem/cramfs.py
+++ b/unblob/handlers/filesystem/cramfs.py
@@ -2,8 +2,6 @@
 import struct
 from typing import Optional
 
-from dissect.cstruct import Instance
-
 from unblob.extractors import Command
 
 from ...file_utils import Endian, convert_int32, get_endian
@@ -59,7 +57,7 @@ def _is_crc_valid(
         self,
         file: File,
         start_offset: int,
-        header: Instance,
+        header,
         endian: Endian,
     ) -> bool:
         # old cramfs format do not support crc
diff --git a/unblob/handlers/filesystem/jffs2.py b/unblob/handlers/filesystem/jffs2.py
index 0b5e3fcf31..77bf8f7a89 100644
--- a/unblob/handlers/filesystem/jffs2.py
+++ b/unblob/handlers/filesystem/jffs2.py
@@ -2,7 +2,6 @@
 import io
 from typing import Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.file_utils import (
@@ -61,7 +60,7 @@ def guess_endian(self, file: File) -> Endian:
         file.seek(-2, io.SEEK_CUR)
         return endian
 
-    def valid_header(self, header: Instance, node_start_offset: int, eof: int) -> bool:
+    def valid_header(self, header, node_start_offset: int, eof: int) -> bool:
         header_crc = (binascii.crc32(header.dumps()[:-4], -1) ^ -1) & 0xFFFFFFFF
         check_crc = True
 
diff --git a/unblob/handlers/filesystem/squashfs.py b/unblob/handlers/filesystem/squashfs.py
index 099f1758bc..d115c35fac 100644
--- a/unblob/handlers/filesystem/squashfs.py
+++ b/unblob/handlers/filesystem/squashfs.py
@@ -1,7 +1,6 @@
 from pathlib import Path
 from typing import List, Optional
 
-from dissect.cstruct import Instance
 from structlog import get_logger
 
 from unblob.extractors import Command
@@ -297,7 +296,7 @@ class SquashFSv4LEHandler(_SquashFSBase):
 class SquashFSv4BEExtractor(Extractor):
     EXECUTABLE = "sasquatch-v4be"
 
-    def is_avm(self, header: Instance) -> bool:
+    def is_avm(self, header) -> bool:
         # see https://raw.githubusercontent.com/Freetz/freetz/master/tools/make/squashfs4-host-be/AVM-BE-format.txt
         return header.bytes_used == header.mkfs_time
 
diff --git a/unblob/handlers/filesystem/yaffs.py b/unblob/handlers/filesystem/yaffs.py
index 966c8eaad5..a8ffcc4e28 100644
--- a/unblob/handlers/filesystem/yaffs.py
+++ b/unblob/handlers/filesystem/yaffs.py
@@ -6,7 +6,6 @@
 from typing import Iterable, List, Optional, Tuple
 
 import attr
-from dissect.cstruct import Instance
 from structlog import get_logger
 from treelib import Tree
 from treelib.exceptions import NodeIDAbsentError
@@ -259,7 +258,7 @@ def valid_name(name: bytes) -> bool:
         return True
 
 
-def is_valid_header(header: Instance) -> bool:
+def is_valid_header(header) -> bool:
     if not valid_name(header.name[:-3]):
         return False
     if header.type > 5:
@@ -284,7 +283,7 @@ def __init__(self, file: File, config: Optional[YAFFSConfig] = None):
         else:
             self.config = config
 
-    def build_entry(self, header: Instance, chunk: YAFFSChunk) -> YAFFSEntry:
+    def build_entry(self, header, chunk: YAFFSChunk) -> YAFFSEntry:
         raise NotImplementedError
 
     def build_chunk(self, spare: bytes, offset: int) -> YAFFSChunk:
@@ -398,7 +397,7 @@ def auto_detect(self) -> YAFFSConfig:
         object_id_offset = 4
         object_id_start = page_size + ecc_offset + object_id_offset
         object_id_end = object_id_start + 4
-        spare_signature = self.file[object_id_start:object_id_end] + b"\xFF\xFF"
+        spare_signature = self.file[object_id_start:object_id_end] + b"\xff\xff"
 
         config.spare_size = (
             self.file[object_id_end : object_id_end + page_size].find(spare_signature)
@@ -459,7 +458,6 @@ def get_entry(self, object_id: int) -> Optional[YAFFSEntry]:
                 "Can't find entry within the YAFFS tree, something's wrong.",
                 object_id=object_id,
             )
-            pass
         return None
 
     def resolve_path(self, entry: YAFFSEntry) -> Path:
@@ -534,7 +532,7 @@ def build_chunk(self, spare: bytes, offset: int) -> YAFFS2Chunk:
             object_id=yaffs2_packed_tags.object_id,
         )
 
-    def build_entry(self, header: Instance, chunk: YAFFSChunk) -> YAFFSEntry:
+    def build_entry(self, header, chunk: YAFFSChunk) -> YAFFSEntry:
         return YAFFS2Entry(
             object_id=chunk.object_id,
             object_type=header.type,
@@ -549,7 +547,7 @@ def build_entry(self, header: Instance, chunk: YAFFSChunk) -> YAFFSEntry:
             st_mtime=header.st_mtime,
             st_ctime=header.st_ctime,
             equiv_id=header.equiv_id,
-            alias=snull(header.alias.replace(b"\xFF", b"")).decode("utf-8"),
+            alias=snull(header.alias.replace(b"\xff", b"")).decode("utf-8"),
             st_rdev=header.st_rdev,
             win_ctime=header.win_ctime,
             win_mtime=header.win_mtime,
@@ -644,14 +642,14 @@ def build_chunk(self, spare: bytes, offset: int) -> YAFFS1Chunk:
             block_status=yaffs_sparse.block_status,
         )
 
-    def build_entry(self, header: Instance, chunk: YAFFSChunk) -> YAFFSEntry:
+    def build_entry(self, header, chunk: YAFFSChunk) -> YAFFSEntry:
         return YAFFSEntry(
             object_type=header.type,
             object_id=chunk.object_id,
             parent_obj_id=header.parent_obj_id,
             sum_no_longer_used=header.sum_no_longer_used,
             name=snull(header.name[0:128]).decode("utf-8"),
-            alias=snull(header.alias.replace(b"\xFF", b"")).decode("utf-8"),
+            alias=snull(header.alias.replace(b"\xff", b"")).decode("utf-8"),
             file_size=header.file_size,
             equiv_id=header.equivalent_object_id,
         )