diff --git a/routstr/lightning.py b/routstr/lightning.py
index a6dd7ec3..6e045925 100644
--- a/routstr/lightning.py
+++ b/routstr/lightning.py
@@ -601,8 +601,20 @@ async def check_invoice_payment(
 
 
 def _is_quote_not_found(error: BaseException) -> bool:
-    """Check if the error indicates the mint no longer has this quote."""
+    """Check if the error indicates the mint no longer has this quote.
+
+    Recognised variants:
+    - ``Mint Error: quote not found (Code: 0)`` (legacy wording) — treated as
+      definitive only with the exact ``0`` code, because some mints reuse the
+      ``quote not found`` wording for ambiguous states.
+    - ``Mint Error: Unknown quote (Code: 50000)`` — reported by some mint
+      implementations when the quote id was never issued or was dropped. The
+      wording itself is definitive (the mint has no record of the quote), and
+      the numeric code varies (seen as ``50000``), so no code check is applied.
+    """
     message = str(error)
+    if re.search(r"\bunknown\s+quote\b", message, re.IGNORECASE):
+        return True
     return bool(
         re.search(r"\bquote\s+not\s+found\b", message, re.IGNORECASE)
         and re.search(r"\bcode\s*:?\s*0\b", message, re.IGNORECASE)
diff --git a/tests/unit/test_lightning_settlement.py b/tests/unit/test_lightning_settlement.py
index f791a2d8..70f4b31a 100644
--- a/tests/unit/test_lightning_settlement.py
+++ b/tests/unit/test_lightning_settlement.py
@@ -217,6 +217,58 @@ async def test_quote_not_found_case_insensitive() -> None:
     assert result is True
 
 
+@pytest.mark.asyncio
+async def test_unknown_quote_is_definitively_unpaid() -> None:
+    """Some mints report a dropped quote as 'Unknown quote (Code: 50000)'."""
+    _invoice_settlement_locks.clear()
+    invoice = _invoice(status="pending", expires_at=0)
+    session = AsyncMock()
+    wallet = Mock(
+        get_mint_quote=AsyncMock(
+            side_effect=Exception("Mint Error: Unknown quote (Code: 50000)")
+        )
+    )
+
+    with (
+        patch("routstr.lightning.get_wallet", AsyncMock(return_value=wallet)),
+        patch("routstr.lightning._reload_invoice_view", AsyncMock()),
+    ):
+        result = await check_invoice_payment(invoice, session)  # type: ignore[arg-type]
+
+    assert result is True
+
+
+@pytest.mark.parametrize(
+    "message",
+    [
+        # legacy wording must still require the exact code 0
+        "Mint Error: quote not found (Code: 10000)",
+        "Mint Error: quote not found (Code: 50000)",
+        # not actually referring to a mint quote id
+        "Mint Error: unknown request",
+        "connection error: quote endpoint unreachable",
+    ],
+)
+def test_unknown_quote_only_matches_real_quote_missing_errors(message: str) -> None:
+    from routstr.lightning import _is_quote_not_found
+
+    assert not _is_quote_not_found(Exception(message))
+
+
+@pytest.mark.parametrize(
+    "message",
+    [
+        "Mint Error: Unknown quote (Code: 50000)",
+        "MINT ERROR: UNKNOWN QUOTE (CODE 50000)",
+        "Mint Error: unknown quote (Code: 11000)",
+    ],
+)
+def test_unknown_quote_wording_is_recognized(message: str) -> None:
+    from routstr.lightning import _is_quote_not_found
+
+    assert _is_quote_not_found(Exception(message))
+
+
 @pytest.mark.asyncio
 async def test_credited_invoice_is_not_minted() -> None:
     _invoice_settlement_locks.clear()