diff --git a/piker/brokers/ib.py b/piker/brokers/ib.py
index 20865e30..b861d895 100644
--- a/piker/brokers/ib.py
+++ b/piker/brokers/ib.py
@@ -996,15 +996,22 @@ async def load_aio_clients(
                         accounts_def.inverse[pp.account]
                     ] = client
 
-            # if there are no positions or accounts
-            # without positions we should still register
-            # them for this client
+            # if there are accounts without positions we should still
+            # register them for this client
             for value in ib.accountValues():
-                acct = value.account
-                if acct not in accounts_found:
-                    accounts_found[
-                        accounts_def.inverse[acct]
-                    ] = client
+                acct_number = value.account
+
+                entry = accounts_def.inverse.get(acct_number)
+                if not entry:
+                    raise ValueError(
+                        'No section in brokers.toml for account:'
+                        f' {acct_number}\n'
+                        f'Please add entry to continue using this API client'
+                    )
+
+                # surjection of account names to operating clients.
+                if acct_number not in accounts_found:
+                    accounts_found[entry] = client
 
             log.info(
                 f'Loaded accounts for client @ {host}:{port}\n'
@@ -1028,6 +1035,8 @@ async def load_aio_clients(
             # torn down correctly ...
             tractor._actor._lifetime_stack.callback(pop_and_discon)
 
+            # XXX: why aren't we just updating this directy above
+            # instead of using the intermediary `accounts_found`?
             _accounts2clients.update(accounts_found)
 
         except (
@@ -2117,6 +2126,7 @@ async def trades_dialogue(
 
     clients: list[tuple[Client, trio.MemoryReceiveChannel]] = []
     async with trio.open_nursery() as nurse:
+
         for account, client in _accounts2clients.items():
 
             async def open_stream(
@@ -2136,11 +2146,18 @@ async def trades_dialogue(
 
             clients.append((client, trade_event_stream))
 
+            assert account in accounts_def
+            accounts.add(account)
+
         for client in _client_cache.values():
             for pos in client.positions():
+
                 msg = pack_position(pos)
                 msg.account = accounts_def.inverse[msg.account]
-                accounts.add(msg.account)
+
+                assert msg.account in accounts, (
+                    f'Position for unknown account: {msg.account}')
+
                 all_positions.append(msg.dict())
 
         await ctx.started((