diff --git a/flowcontrol/flow_control_manager.go b/flowcontrol/flow_control_manager.go
index d9f4af21f..c5b4e7541 100644
--- a/flowcontrol/flow_control_manager.go
+++ b/flowcontrol/flow_control_manager.go
@@ -157,6 +157,11 @@ func (f *flowControlManager) GetReceiveWindow(streamID protocol.StreamID) (proto
 	f.mutex.RLock()
 	defer f.mutex.RUnlock()
 
+	// StreamID can be 0 when retransmitting
+	if streamID == 0 {
+		return f.connFlowController.receiveWindow, nil
+	}
+
 	flowController, err := f.getFlowController(streamID)
 	if err != nil {
 		return 0, err
diff --git a/flowcontrol/flow_control_manager_test.go b/flowcontrol/flow_control_manager_test.go
index 92fde3b25..b0a2a8999 100644
--- a/flowcontrol/flow_control_manager_test.go
+++ b/flowcontrol/flow_control_manager_test.go
@@ -103,6 +103,12 @@ var _ = Describe("Flow Control Manager", func() {
 			Expect(err).To(MatchError(errMapAccess))
 		})
 
+		It("gets the offset of the connection-level receive window", func() {
+			offset, err := fcm.GetReceiveWindow(0)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(offset).To(Equal(protocol.ByteCount(200)))
+		})
+
 		Context("flow control violations", func() {
 			It("errors when encountering a stream level flow control violation", func() {
 				err := fcm.UpdateHighestReceived(4, 101)