diff --git a/src/python/grpcio/grpc/_server.py b/src/python/grpcio/grpc/_server.py
index b58201b79d0..b1b6027ed5a 100644
--- a/src/python/grpcio/grpc/_server.py
+++ b/src/python/grpcio/grpc/_server.py
@@ -391,11 +391,11 @@ def _call_behavior(rpc_event,
                    behavior,
                    argument,
                    request_deserializer,
-                   stream_observer=None):
+                   on_next_callback=None):
     context = _Context(rpc_event, state, request_deserializer)
     try:
-        if stream_observer is not None:
-            return behavior(argument, context, stream_observer), True
+        if on_next_callback is not None:
+            return behavior(argument, context, on_next_callback), True
         else:
             return behavior(argument, context), True
     except Exception as exception:  # pylint: disable=broad-except
@@ -530,7 +530,7 @@ def _stream_response_in_pool(rpc_event, state, behavior, argument_thunk,
                     behavior,
                     argument,
                     request_deserializer,
-                    stream_observer=on_next)
+                    on_next_callback=on_next)
             else:
                 response_iterator, proceed = _call_behavior(
                     rpc_event, state, behavior, argument, request_deserializer)
@@ -545,13 +545,13 @@ def _is_rpc_state_active(state):
     return state.client is not _CANCELLED and not state.statused
 
 
-def _stream_response_iterator_adapter(rpc_event, state, stream_observer,
+def _stream_response_iterator_adapter(rpc_event, state, on_next_callback,
                                       response_iterator):
     while True:
         response, proceed = _take_response_from_response_iterator(
             rpc_event, state, response_iterator)
         if proceed:
-            stream_observer(response)
+            on_next_callback(response)
             if not _is_rpc_state_active(state):
                 break
         else: