diff --git a/piker/exchange/_paper_engine.py b/piker/exchange/_paper_engine.py
index 06499732..740345f5 100644
--- a/piker/exchange/_paper_engine.py
+++ b/piker/exchange/_paper_engine.py
@@ -70,15 +70,15 @@ class PaperBoi:
         if brid is None:
             reqid = str(uuid.uuid4())
 
-            # register order internally
-            self._reqids[reqid] = (oid, symbol, action, price)
-
         else:
             # order is already existing, this is a modify
             (oid, symbol, action, old_price) = self._reqids[brid]
             assert old_price != price
             reqid = brid
 
+        # register order internally
+        self._reqids[reqid] = (oid, symbol, action, price)
+
         if action == 'alert':
             # bypass all fill simulation
             return reqid
@@ -129,6 +129,10 @@ class PaperBoi:
             # and trigger by the simulated clearing task normally
             # running ``simulate_fills()``.
 
+            if brid is not None:
+                # remove any existing order for the old price
+                orders[symbol].pop((oid, old_price))
+
             # buys/sells: (symbol  -> (price -> order))
             orders.setdefault(symbol, {})[(oid, price)] = (size, reqid, action)