diff --git a/lib/src/http_connection.dart b/lib/src/http_connection.dart
index 0f4c55e..46c8a08 100644
--- a/lib/src/http_connection.dart
+++ b/lib/src/http_connection.dart
@@ -635,7 +635,10 @@ class TransportSendQueue {
     }
 
     _buffer.add(data);
-    _sendBufferedData.complete();
+    
+    if(!_sendBufferedData.isCompleted) {
+      _sendBufferedData.complete();
+    }
   }
 
   Future<void> sendLoop() async {