diff --git a/chia-blockchain-gui b/chia-blockchain-gui
index 4969c3b9186c..4a2a72504a3a 160000
--- a/chia-blockchain-gui
+++ b/chia-blockchain-gui
@@ -1 +1 @@
-Subproject commit 4969c3b9186cf1db87a79ad0486b51327f8375dc
+Subproject commit 4a2a72504a3a4efe73c7aa037bffd4fa41cdf5e3
diff --git a/chia/_tests/core/mempool/test_singleton_fast_forward.py b/chia/_tests/core/mempool/test_singleton_fast_forward.py
index f96e31bf44fe..be56a39a1a34 100644
--- a/chia/_tests/core/mempool/test_singleton_fast_forward.py
+++ b/chia/_tests/core/mempool/test_singleton_fast_forward.py
@@ -663,4 +663,4 @@ async def test_double_spend_ff_spend_no_latest_unspent() -> None:
         status, error = await make_and_send_spend_bundle(sim, sim_client, [singleton_coin_spend], aggsig=sig)
         # It fails validation because it doesn't currently have a latest unspent
         assert status == MempoolInclusionStatus.FAILED
-        assert error == Err.DOUBLE_SPEND
+        assert error == Err.UNKNOWN_UNSPENT
diff --git a/chia/full_node/coin_store.py b/chia/full_node/coin_store.py
index f2da3b66f644..f372be2756b1 100644
--- a/chia/full_node/coin_store.py
+++ b/chia/full_node/coin_store.py
@@ -30,6 +30,9 @@ class CoinStore:
     """
 
     db_wrapper: DBWrapper2
+    # Fall back to the `coin_puzzle_hash` index if the ff unspent index
+    # does not exist.
+    _unspent_lineage_for_ph_idx: str = "coin_puzzle_hash"
 
     @classmethod
     async def create(cls, db_wrapper: DBWrapper2) -> CoinStore:
@@ -82,6 +85,12 @@ async def create(cls, db_wrapper: DBWrapper2) -> CoinStore:
                         WHERE spent_index = -1
                     """
                 )
+            async with conn.execute(
+                "SELECT 1 FROM sqlite_master WHERE type = 'index' AND name = 'coin_record_ph_ff_unspent_idx'"
+            ) as cursor:
+                has_ff_unspent_idx = await cursor.fetchone() is not None
+            if has_ff_unspent_idx:
+                self._unspent_lineage_for_ph_idx = "coin_record_ph_ff_unspent_idx"
 
         return self
 
@@ -639,6 +648,7 @@ async def get_unspent_lineage_info_for_puzzle_hash(self, puzzle_hash: bytes32) -
                 "unspent.coin_parent, "
                 "parent.coin_parent "
                 "FROM coin_record AS unspent "
+                f"INDEXED BY {self._unspent_lineage_for_ph_idx} "
                 "LEFT JOIN coin_record AS parent ON unspent.coin_parent = parent.coin_name "
                 "WHERE unspent.spent_index = -1 "
                 "AND parent.spent_index > 0 "
diff --git a/chia/full_node/mempool_manager.py b/chia/full_node/mempool_manager.py
index 3ce59c942cb2..6908fb088e40 100644
--- a/chia/full_node/mempool_manager.py
+++ b/chia/full_node/mempool_manager.py
@@ -640,7 +640,7 @@ async def validate_spend_bundle(
                 assert eligibility_info.ff_puzzle_hash is not None
                 lineage_info = await get_unspent_lineage_info_for_puzzle_hash(eligibility_info.ff_puzzle_hash)
                 if lineage_info is None:
-                    return Err.DOUBLE_SPEND, None, []
+                    mark_as_fast_forward = False
             bundle_coin_spends[coin_id] = BundleCoinSpend(
                 coin_spend=coin_spend,
                 eligible_for_dedup=supports_dedup,