diff --git a/src/nucleus/response/stream.py b/src/nucleus/response/stream.py
index cc90307..83c2892 100644
--- a/src/nucleus/response/stream.py
+++ b/src/nucleus/response/stream.py
@@ -103,10 +103,11 @@ class ResponseStream:
     def __iter__(self):
         self.status = 'running'
         self.position = 'status'
-        if isinstance(self.data, str):
+        response = self.response
+        if isinstance(response.data, str):
             self.__next__ = str_next
-        elif isinstance(self.data, BufferedReader):
+        elif isinstance(response.data, BufferedReader):
             self.__next__ = stream_next
-        elif isinstance(self.data, bytes):
+        elif isinstance(response.data, bytes):
             self.__next__ = bytes_next
         return self