diff --git a/mango/inventory.py b/mango/inventory.py
index 8273389..1057c38 100644
--- a/mango/inventory.py
+++ b/mango/inventory.py
@@ -23,8 +23,11 @@ from .account import Account
 from .cache import Cache
 from .group import Group
 from .instrumentvalue import InstrumentValue
-from .markets import InventorySource, Market
+from .loadedmarket import LoadedMarket
+from .markets import InventorySource
 from .openorders import OpenOrders
+from .perpmarket import PerpMarket
+from .spotmarket import SpotMarket
 from .watcher import Watcher
 
 
@@ -65,7 +68,7 @@ class Inventory:
 class InventoryAccountWatcher:
     def __init__(
         self,
-        market: Market,
+        market: LoadedMarket,
         account_watcher: Watcher[Account],
         group_watcher: Watcher[Group],
         all_open_orders_watchers: typing.Sequence[Watcher[OpenOrders]],
@@ -78,9 +81,19 @@ class InventoryAccountWatcher:
         ] = all_open_orders_watchers
         self.cache_watcher: Watcher[Cache] = cache_watcher
         account: Account = account_watcher.latest
-        self.spot_account_index: int = group_watcher.latest.slot_by_spot_market_address(
-            market.address
-        ).index
+        if SpotMarket.isa(market):
+            self.spot_account_index: int = (
+                group_watcher.latest.slot_by_spot_market_address(market.address).index
+            )
+        elif PerpMarket.isa(market):
+            self.spot_account_index = group_watcher.latest.slot_by_spot_market_address(
+                market.address
+            ).index
+        else:
+            raise Exception(
+                f"Cannot find slot for market {market} in group {group_watcher.latest.address}"
+            )
+
         base_value = InstrumentValue.find_by_symbol(
             account.net_values, market.base.symbol
         )