diff --git a/aiohttp/connector.py b/aiohttp/connector.py
index 9ea367bb425..b4065b492bd 100644
--- a/aiohttp/connector.py
+++ b/aiohttp/connector.py
@@ -375,10 +375,13 @@ def connect(self, req):
             # This connection will now count towards the limit.
             waiters = self._waiters[key]
             waiters.append(fut)
-            yield from fut
-            waiters.remove(fut)
-            if not waiters:
-                del self._waiters[key]
+            try:
+                yield from fut
+            finally:
+                # remove a waiter even if it was cancelled
+                waiters.remove(fut)
+                if not waiters:
+                    del self._waiters[key]
 
         proto = self._get(key)
         if proto is None:
@@ -390,6 +393,13 @@ def connect(self, req):
                 if self._closed:
                     proto.close()
                     raise ClientConnectionError("Connector is closed.")
+            except:
+                # signal to waiter
+                for waiter in self._waiters[key]:
+                    if not waiter.done():
+                        waiter.set_result(None)
+                        break
+                raise
             finally:
                 if not self._closed:
                     self._acquired.remove(placeholder)
diff --git a/tests/test_connector.py b/tests/test_connector.py
index 2cae8b8d768..68167174e68 100644
--- a/tests/test_connector.py
+++ b/tests/test_connector.py
@@ -1173,6 +1173,100 @@ def test_force_close_and_explicit_keep_alive(loop):
     assert conn
 
 
+@asyncio.coroutine
+def test_error_on_connection(loop):
+    conn = aiohttp.BaseConnector(limit=1, loop=loop)
+
+    req = mock.Mock()
+    req.connection_key = 'key'
+    proto = mock.Mock()
+    i = 0
+
+    fut = helpers.create_future(loop=loop)
+    exc = OSError()
+
+    @asyncio.coroutine
+    def create_connection(req):
+        nonlocal i
+        i += 1
+        if i == 1:
+            yield from fut
+            raise exc
+        elif i == 2:
+            return proto
+
+    conn._create_connection = create_connection
+
+    t1 = helpers.ensure_future(conn.connect(req), loop=loop)
+    t2 = helpers.ensure_future(conn.connect(req), loop=loop)
+    yield from asyncio.sleep(0, loop=loop)
+    assert not t1.done()
+    assert not t2.done()
+    assert len(conn._acquired_per_host['key']) == 1
+
+    fut.set_result(None)
+    with pytest.raises(OSError):
+        yield from t1
+
+    ret = yield from t2
+    assert len(conn._acquired_per_host['key']) == 1
+
+    assert ret._key == 'key'
+    assert ret.protocol == proto
+    assert proto in conn._acquired
+
+
+@asyncio.coroutine
+def test_error_on_connection_with_cancelled_waiter(loop):
+    conn = aiohttp.BaseConnector(limit=1, loop=loop)
+
+    req = mock.Mock()
+    req.connection_key = 'key'
+    proto = mock.Mock()
+    i = 0
+
+    fut1 = helpers.create_future(loop=loop)
+    fut2 = helpers.create_future(loop=loop)
+    exc = OSError()
+
+    @asyncio.coroutine
+    def create_connection(req):
+        nonlocal i
+        i += 1
+        if i == 1:
+            yield from fut1
+            raise exc
+        if i == 2:
+            yield from fut2
+        elif i == 3:
+            return proto
+
+    conn._create_connection = create_connection
+
+    t1 = helpers.ensure_future(conn.connect(req), loop=loop)
+    t2 = helpers.ensure_future(conn.connect(req), loop=loop)
+    t3 = helpers.ensure_future(conn.connect(req), loop=loop)
+    yield from asyncio.sleep(0, loop=loop)
+    assert not t1.done()
+    assert not t2.done()
+    assert len(conn._acquired_per_host['key']) == 1
+
+    fut1.set_result(None)
+    fut2.cancel()
+    with pytest.raises(OSError):
+        yield from t1
+
+    with pytest.raises(asyncio.CancelledError):
+        yield from t2
+
+    ret = yield from t3
+    assert len(conn._acquired_per_host['key']) == 1
+
+    assert ret._key == 'key'
+    assert ret.protocol == proto
+    assert proto in conn._acquired
+
+
 @asyncio.coroutine
 def test_tcp_connector(test_client, loop):
     @asyncio.coroutine