diff --git a/pcapkit/protocols/internet/hopopt.py b/pcapkit/protocols/internet/hopopt.py
index 1ef8bae70a..fc3bdaef82 100644
--- a/pcapkit/protocols/internet/hopopt.py
+++ b/pcapkit/protocols/internet/hopopt.py
@@ -1611,8 +1611,9 @@ def _make_opt_smf_dpd(self, code: 'Enum_Option', opt: 'Optional[Data_SMFIdentifi
             Constructed option schema.
 
         Raises:
-            ProtocolError: If the DPD mode is invalid, or the Tagger ID does
-                not fit the TaggerID type.
+            ProtocolError: If the DPD mode is invalid, the Tagger ID does
+                not fit the TaggerID type, or the H-DPD Hash Assist Value is
+                empty.
 
         """
         if opt is not None:
@@ -1673,6 +1674,9 @@ def _make_opt_smf_dpd(self, code: 'Enum_Option', opt: 'Optional[Data_SMFIdentifi
                 id=id,
             )  # type: Schema_SMFDPDOption
         elif dpd_type == Enum_SMFDPDMode.H_DPD:
+            # The first octet of the HAV carries the H-DPD mode bit.
+            if not hav:
+                raise ProtocolError(f'{self.alias}: [OptNo {code}] empty Hash Assist Value (HAV)')
             hav_ba = bytearray(hav)
             hav_ba[0] = hav[0] | 0x80
 
diff --git a/pcapkit/protocols/internet/ipv6_opts.py b/pcapkit/protocols/internet/ipv6_opts.py
index 22c53e8961..a8e267bdbe 100644
--- a/pcapkit/protocols/internet/ipv6_opts.py
+++ b/pcapkit/protocols/internet/ipv6_opts.py
@@ -1600,8 +1600,9 @@ def _make_opt_smf_dpd(self, code: 'Enum_Option', opt: 'Optional[Data_SMFIdentifi
             Constructed option schema.
 
         Raises:
-            ProtocolError: If the DPD mode is invalid, or the Tagger ID does
-                not fit the TaggerID type.
+            ProtocolError: If the DPD mode is invalid, the Tagger ID does
+                not fit the TaggerID type, or the H-DPD Hash Assist Value is
+                empty.
 
         """
         if opt is not None:
@@ -1662,6 +1663,9 @@ def _make_opt_smf_dpd(self, code: 'Enum_Option', opt: 'Optional[Data_SMFIdentifi
                 id=id,
             )  # type: Schema_SMFDPDOption
         elif dpd_type == Enum_SMFDPDMode.H_DPD:
+            # The first octet of the HAV carries the H-DPD mode bit.
+            if not hav:
+                raise ProtocolError(f'{self.alias}: [OptNo {code}] empty Hash Assist Value (HAV)')
             hav_ba = bytearray(hav)
             hav_ba[0] = hav[0] | 0x80
 
diff --git a/tests/protocols/internet/test_smf_dpd_empty_hav_unit.py b/tests/protocols/internet/test_smf_dpd_empty_hav_unit.py
new file mode 100644
index 0000000000..5874bc78df
--- /dev/null
+++ b/tests/protocols/internet/test_smf_dpd_empty_hav_unit.py
@@ -0,0 +1,59 @@
+# -*- coding: utf-8 -*-
+"""HOPOPT and IPv6-Opts reject an H-DPD SMF_DPD option with an empty HAV.
+
+GitHub issue #1193: ``_make_opt_smf_dpd`` set the H-DPD mode bit with
+``hav[0] | 0x80`` and no length check, so an empty Hash Assist Value raised a
+bare :exc:`IndexError` rather than an in-library
+:exc:`~pcapkit.utilities.exceptions.ProtocolError`.
+
+Every case builds its options in memory and reads no capture. The protocol
+classes are imported inside each test, after
+:func:`~tests._support.reimport_once_per_class`, as in
+:mod:`tests.protocols.link.test_ethernet_mac_roundtrip_unit`.
+
+"""
+
+import unittest
+
+from tests._support import reimport_once_per_class
+
+
+def _classes() -> 'dict[str, type]':
+    from pcapkit.protocols.internet.hopopt import HOPOPT
+    from pcapkit.protocols.internet.ipv6_opts import IPv6_Opts
+    return {'HOPOPT': HOPOPT, 'IPv6_Opts': IPv6_Opts}
+
+
+class TestSMFDPDEmptyHAV(unittest.TestCase):
+    """Pin the error raised for an empty H-DPD Hash Assist Value."""
+
+    def setUp(self) -> None:
+        reimport_once_per_class(self)
+
+    def test_empty_hav_raises_protocol_error(self) -> None:
+        from pcapkit.const.ipv6.option import Option
+        from pcapkit.const.ipv6.smf_dpd_mode import SMFDPDMode
+        from pcapkit.const.reg.transtype import TransType
+        from pcapkit.utilities.exceptions import ProtocolError
+
+        for name, cls in _classes().items():
+            with self.subTest(proto=name):
+                with self.assertRaisesRegex(ProtocolError, r'\[OptNo 8\] empty Hash Assist Value'):
+                    cls(options=[(Option.SMF_DPD, {'mode': SMFDPDMode.H_DPD, 'hav': b''})],
+                        next=TransType.IPv6_NoNxt, payload=b'')
+
+    def test_one_octet_hav_still_builds(self) -> None:
+        from pcapkit.const.ipv6.option import Option
+        from pcapkit.const.ipv6.smf_dpd_mode import SMFDPDMode
+        from pcapkit.const.reg.transtype import TransType
+
+        for name, cls in _classes().items():
+            with self.subTest(proto=name):
+                built = cls(options=[(Option.SMF_DPD, {'mode': SMFDPDMode.H_DPD, 'hav': b'\x01'})],
+                            next=TransType.IPv6_NoNxt, payload=b'')
+                # SMF_DPD, length 1, HAV 0x01 with the H-DPD bit set, then PadN.
+                self.assertEqual(built.data, bytes.fromhex('3b00080181010100'))
+
+
+if __name__ == '__main__':
+    unittest.main()