diff --git a/blender_asset_tracer/blendfile/__init__.py b/blender_asset_tracer/blendfile/__init__.py
index e09ce3f..3b23c81 100644
--- a/blender_asset_tracer/blendfile/__init__.py
+++ b/blender_asset_tracer/blendfile/__init__.py
@@ -447,6 +447,12 @@ class BlendFileBlock:
     old_structure = struct.Struct(b"4sI")
     """old blend files ENDB block structure"""
 
+    # Explicitly annotate to avoid `Any` from `.unpack()`.
+    size: int
+    addr_old: int
+    sdna_index: int
+    count: int
+
     def __init__(self, bfile: BlendFile) -> None:
         self.bfile = bfile
 
diff --git a/blender_asset_tracer/blendfile/dna_io.py b/blender_asset_tracer/blendfile/dna_io.py
index d675b6b..9399942 100644
--- a/blender_asset_tracer/blendfile/dna_io.py
+++ b/blender_asset_tracer/blendfile/dna_io.py
@@ -204,17 +204,17 @@ class EndianIO:
         return fileobj.write(to_write)
 
     @classmethod
-    def read_bytes0(cls, fileobj, length):
+    def read_bytes0(cls, fileobj: typing.IO[bytes], length: int) -> bytes:
         data = fileobj.read(length)
         return cls.read_data0(data)
 
     @classmethod
-    def read_data0_offset(cls, data, offset):
+    def read_data0_offset(cls, data: bytes, offset: int) -> bytes:
         add = data.find(b"\0", offset) - offset
         return data[offset : offset + add]
 
     @classmethod
-    def read_data0(cls, data):
+    def read_data0(cls, data: bytes) -> bytes:
         add = data.find(b"\0")
         if add < 0:
             return data