diff --git a/torba/baseledger.py b/torba/baseledger.py
index 7a25af41e..99fb5f1d1 100644
--- a/torba/baseledger.py
+++ b/torba/baseledger.py
@@ -105,7 +105,7 @@ class BaseLedger:
         if address not in self.addresses:
             self.addresses[address] = Address(self.coin_class.address_to_hash160(address))
         self.addresses[address].add_transaction(transaction)
-        self.transactions.setdefault(hexlify(transaction.id), transaction)
+        self.transactions.setdefault(transaction.id, transaction)
         self._on_transaction_controller.add(transaction)
 
     def has_address(self, address):
diff --git a/torba/basetransaction.py b/torba/basetransaction.py
index af854e970..ee23b0929 100644
--- a/torba/basetransaction.py
+++ b/torba/basetransaction.py
@@ -1,7 +1,7 @@
 import six
 import logging
 from typing import List
-from collections import namedtuple
+from binascii import hexlify
 
 from torba.basecoin import BaseCoin
 from torba.basescript import BaseInputScript, BaseOutputScript
@@ -161,7 +161,7 @@ class BaseTransaction:
     @property
     def id(self):
         if self._id is None:
-            self._id = self.hash[::-1]
+            self._id = hexlify(self.hash[::-1])
         return self._id
 
     @property
diff --git a/torba/stream.py b/torba/stream.py
index 0f089dc5f..a5f3f63c9 100644
--- a/torba/stream.py
+++ b/torba/stream.py
@@ -1,6 +1,10 @@
+import six
 from twisted.internet.defer import Deferred, DeferredLock, maybeDeferred, inlineCallbacks
 from twisted.python.failure import Failure
 
+if six.PY3:
+    import asyncio
+
 
 def execute_serially(f):
     _lock = DeferredLock()
@@ -124,6 +128,23 @@ class Stream:
     def listen(self, on_data, on_error=None, on_done=None):
         return self._controller._listen(on_data, on_error, on_done)
 
+    def where(self, condition):
+        deferred = Deferred()
+
+        def where_test(value):
+            if condition(value):
+                self._cancel_and_callback(subscription, deferred, value)
+
+        subscription = self.listen(
+            where_test,
+            lambda error, traceback: self._cancel_and_error(subscription, deferred, error, traceback)
+        )
+
+        return deferred
+
+    def async_where(self, condition):
+        return self.where(condition).asFuture(asyncio.get_event_loop())
+
     @property
     def first(self):
         deferred = Deferred()