diff --git a/pcapkit/protocols/protocol.py b/pcapkit/protocols/protocol.py
index e25506d6b7..40d5885130 100644
--- a/pcapkit/protocols/protocol.py
+++ b/pcapkit/protocols/protocol.py
@@ -1811,12 +1811,19 @@ def _read_binary(self, size: 'int' = 1) -> 'str':
         Returns:
             Binary bits (``0``/``1``).
 
+        Raises:
+            StructError: If the buffer is empty, with ``eof`` set as by
+                :meth:`_read_unpack`, or if fewer than ``size`` octets were read.
+
         """
-        bin_ = []  # type: list[str]
-        for _ in range(size):
-            byte = self._file.read(1)
-            bin_.append(bin(ord(byte))[2:].zfill(8))
-        return ''.join(bin_)
+        # ``max`` makes a non-positive size read nothing rather than the
+        # rest of the stream.
+        mem = self._file.read(max(size, 0))
+        if len(mem) < size:
+            if not mem:
+                raise StructError('unpack: empty buffer', quiet=True, eof=True)
+            raise StructError(f'{self.__class__.__name__}: unpack failed')
+        return ''.join(bin(byte)[2:].zfill(8) for byte in mem)
 
     @overload  # pragma: no cover
     def _read_packet(self, length: 'Optional[int]' = ..., *, header: 'None' = ...) -> 'bytes': ...
diff --git a/tests/protocols/test_protocol_base_unit.py b/tests/protocols/test_protocol_base_unit.py
index 257b9bfb07..e8d93e5dc9 100644
--- a/tests/protocols/test_protocol_base_unit.py
+++ b/tests/protocols/test_protocol_base_unit.py
@@ -357,6 +357,28 @@ def __index__(cls) -> int:
         no_stop._exproto = 'raw'
         self.assertFalse(no_stop._check_term_threshold())
 
+    def test_read_binary_raises_struct_error_at_end_of_stream(self) -> None:
+        # #2292: _read_binary called ord() on an empty read and raised
+        # TypeError, where _read_unpack raises StructError.
+        DummyProtocol, _, _ = self._make_protocol_class()
+        from pcapkit.utilities.exceptions import StructError
+
+        proto = DummyProtocol(packet=b'\x01')
+        proto._file = io.BytesIO(b'')
+        with self.assertRaises(StructError) as context:
+            proto._read_binary()
+        self.assertTrue(context.exception.eof)
+
+        proto._file = io.BytesIO(b'\x01')
+        with self.assertRaises(StructError) as context:
+            proto._read_binary(2)
+        self.assertFalse(context.exception.eof)
+
+        proto._file = io.BytesIO(b'\x01\x80\xff')
+        self.assertEqual(proto._read_binary(0), '')
+        self.assertEqual(proto._read_binary(2), '0000000110000000')
+        self.assertEqual(proto._file.read(), b'\xff')
+
     def test_register_stays_quiet_on_same_object_reregistration(self) -> None:
         """GitHub issue #718: replaying a call with the identical class is a no-op.