diff --git a/consumer/api/python/asapo_consumer.pyx.in b/consumer/api/python/asapo_consumer.pyx.in
index f56c264bf66fd1e3cb04132941535b5ff4a18264..3ff5c94c119150f778d7f086d80a57bd62d2c631 100644
--- a/consumer/api/python/asapo_consumer.pyx.in
+++ b/consumer/api/python/asapo_consumer.pyx.in
@@ -229,7 +229,7 @@ cdef class PyConsumer:
             err = self.c_consumer.get().Acknowledge(b_group_id,id,b_stream)
         if err:
             throw_exception(err)
-    def neg_acknowledge(self, group_id, uint64_t id, uint64_t delay_ms, stream = "default"):
+    def neg_acknowledge(self, group_id, uint64_t id, uint64_t delay_ms = 0, stream = "default"):
         cdef string b_group_id = _bytes(group_id)
         cdef string b_stream = _bytes(stream)
         cdef Error err