diff --git a/bellows/ezsp/v4/__init__.py b/bellows/ezsp/v4/__init__.py
index b70b2664..ebf18001 100644
--- a/bellows/ezsp/v4/__init__.py
+++ b/bellows/ezsp/v4/__init__.py
@@ -217,6 +217,10 @@ async def set_extended_timeout(
         )
 
         if t.sl_Status.from_ember_status(status) != t.sl_Status.OK:
+            # Last-ditch effort
+            await self.setExtendedTimeout(
+                remoteEui64=ieee, extendedTimeout=extended_timeout
+            )
             return
 
         # Replace a random entry in the address table
diff --git a/tests/test_application.py b/tests/test_application.py
index c846f6bf..fce1a8b0 100644
--- a/tests/test_application.py
+++ b/tests/test_application.py
@@ -178,6 +178,7 @@ def form_network():
     )
 
     proto.factory_reset = AsyncMock(proto=proto.factory_reset)
+    proto.set_extended_timeout = AsyncMock(proto=proto.set_extended_timeout)
 
     proto.read_link_keys = MagicMock()
     proto.read_link_keys.return_value.__aiter__.return_value = [
diff --git a/tests/test_ezsp_v4.py b/tests/test_ezsp_v4.py
index 69e00243..3f035366 100644
--- a/tests/test_ezsp_v4.py
+++ b/tests/test_ezsp_v4.py
@@ -1,5 +1,5 @@
 import logging
-from unittest.mock import MagicMock, call
+from unittest.mock import MagicMock, call, patch
 
 import pytest
 import zigpy.state
@@ -379,3 +379,110 @@ async def test_read_counters(ezsp_f, length: int) -> None:
     )
 
     assert counters1 == counters2 == {t.EmberCounterType(i): i for i in range(length)}
+
+
+async def test_set_extended_timeout_no_entry(ezsp_f) -> None:
+    # Typical invocation
+    ezsp_f.getExtendedTimeout.return_value = (t.Bool.false,)
+    ezsp_f.lookupNodeIdByEui64.return_value = (0xFFFF,)  # No address table entry
+    ezsp_f.getConfigurationValue.return_value = (t.EmberStatus.SUCCESS, 8)
+    ezsp_f.replaceAddressTableEntry.return_value = (
+        t.EmberStatus.SUCCESS,
+        t.EUI64.convert("ff:ff:ff:ff:ff:ff:ff:ff"),
+        0xFFFF,
+        t.Bool.false,
+    )
+
+    with patch("bellows.ezsp.v4.random.randint") as mock_random:
+        mock_random.return_value = 0
+        await ezsp_f.set_extended_timeout(
+            nwk=0x1234,
+            ieee=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"),
+            extended_timeout=True,
+        )
+
+    assert ezsp_f.getExtendedTimeout.mock_calls == [
+        call(remoteEui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"))
+    ]
+    assert ezsp_f.lookupNodeIdByEui64.mock_calls == [
+        call(eui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"))
+    ]
+    assert ezsp_f.getConfigurationValue.mock_calls == [
+        call(t.EzspConfigId.CONFIG_ADDRESS_TABLE_SIZE)
+    ]
+    assert mock_random.mock_calls == [call(0, 8 - 1)]
+    assert ezsp_f.replaceAddressTableEntry.mock_calls == [
+        call(
+            addressTableIndex=0,
+            newEui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"),
+            newId=0x1234,
+            newExtendedTimeout=True,
+        )
+    ]
+
+
+async def test_set_extended_timeout_already_set(ezsp_f) -> None:
+    # No-op, it's already set
+    ezsp_f.setExtendedTimeout.return_value = ()
+    ezsp_f.getExtendedTimeout.return_value = (t.Bool.true,)
+
+    await ezsp_f.set_extended_timeout(
+        nwk=0x1234,
+        ieee=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"),
+        extended_timeout=True,
+    )
+
+    assert ezsp_f.getExtendedTimeout.mock_calls == [
+        call(remoteEui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"))
+    ]
+    assert ezsp_f.setExtendedTimeout.mock_calls == []
+
+
+async def test_set_extended_timeout_already_have_entry(ezsp_f) -> None:
+    # An address table entry is present
+    ezsp_f.setExtendedTimeout.return_value = ()
+    ezsp_f.getExtendedTimeout.return_value = (t.Bool.false,)
+    ezsp_f.lookupNodeIdByEui64.return_value = (0x1234,)
+
+    await ezsp_f.set_extended_timeout(
+        nwk=0x1234,
+        ieee=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"),
+        extended_timeout=True,
+    )
+
+    assert ezsp_f.getExtendedTimeout.mock_calls == [
+        call(remoteEui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"))
+    ]
+    assert ezsp_f.lookupNodeIdByEui64.mock_calls == [
+        call(eui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"))
+    ]
+    assert ezsp_f.setExtendedTimeout.mock_calls == [
+        call(
+            remoteEui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"), extendedTimeout=True
+        )
+    ]
+
+
+async def test_set_extended_timeout_bad_table_size(ezsp_f) -> None:
+    ezsp_f.setExtendedTimeout.return_value = ()
+    ezsp_f.getExtendedTimeout.return_value = (t.Bool.false,)
+    ezsp_f.lookupNodeIdByEui64.return_value = (0xFFFF,)
+    ezsp_f.getConfigurationValue.return_value = (t.EmberStatus.ERR_FATAL, 0xFF)
+
+    with patch("bellows.ezsp.v4.random.randint") as mock_random:
+        mock_random.return_value = 0
+        await ezsp_f.set_extended_timeout(
+            nwk=0x1234,
+            ieee=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"),
+            extended_timeout=True,
+        )
+
+    assert ezsp_f.getExtendedTimeout.mock_calls == [
+        call(remoteEui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"))
+    ]
+    assert ezsp_f.lookupNodeIdByEui64.mock_calls == [
+        call(eui64=t.EUI64.convert("aa:bb:cc:dd:ee:ff:00:11"))
+    ]
+    assert ezsp_f.getConfigurationValue.mock_calls == [
+        call(t.EzspConfigId.CONFIG_ADDRESS_TABLE_SIZE)
+    ]