diff --git a/twitter/streams.go b/twitter/streams.go
index 9d1e386..6a96ad6 100644
--- a/twitter/streams.go
+++ b/twitter/streams.go
@@ -156,6 +156,7 @@ type Stream struct {
 	group    *sync.WaitGroup
 	body     io.Closer
 	expected bool
+	mutex    sync.Mutex
 }
 
 // newStream creates a Stream and starts a goroutine to retry connecting and
@@ -176,6 +177,7 @@ func newStream(client *http.Client, req *http.Request, expBackoff, aggExpBackoff
 // Stop signals retry and receiver to stop, closes the Messages channel, and
 // blocks until done.
 func (s *Stream) Stop() {
+	s.mutex.Lock()
 	s.expected = true
 	close(s.done)
 	// Scanner does not have a Stop() or take a done channel, so for low volume
@@ -184,6 +186,7 @@ func (s *Stream) Stop() {
 	if s.body != nil {
 		s.body.Close()
 	}
+	s.mutex.Unlock()
 	// block until the retry goroutine stops
 	s.group.Wait()
 }
@@ -191,7 +194,10 @@ func (s *Stream) Stop() {
 // ExpectedStop indicates whether Stream halting was due to an expected Stop()
 // or some error condition.
 func (s *Stream) ExpectedStop() bool {
-	return s.expected
+	s.mutex.Lock()
+	result := s.expected
+	s.mutex.Unlock()
+	return result
 }
 
 // retry retries making the given http.Request and receiving the response
@@ -213,7 +219,9 @@ func (s *Stream) retry(req *http.Request, expBackOff backoff.BackOff, aggExpBack
 		}
 		// when err is nil, resp contains a non-nil Body which must be closed
 		defer resp.Body.Close()
+		s.mutex.Lock()
 		s.body = resp.Body
+		s.mutex.Unlock()
 		switch resp.StatusCode {
 		case 200:
 			// receive stream response Body, handles closing
diff --git a/twitter/streams_test.go b/twitter/streams_test.go
index 80b3a5e..f46daf8 100644
--- a/twitter/streams_test.go
+++ b/twitter/streams_test.go
@@ -128,12 +128,16 @@ func TestStream_Filter(t *testing.T) {
 	stream, err := client.Streams.Filter(streamFilterParams)
 	// assert that the expected messages are received
 	assert.NoError(t, err)
-	defer stream.Stop()
 	for message := range stream.Messages {
 		demux.Handle(message)
 	}
 	expectedCounts := &counter{all: 3, other: 3}
 	assert.Equal(t, expectedCounts, counts)
+
+	// test ExpectedStop
+	assert.False(t, stream.ExpectedStop())
+	stream.Stop()
+	assert.True(t, stream.ExpectedStop())
 }
 
 func TestStream_Sample(t *testing.T) {