diff --git a/s3tests_boto3/functional/test_headers.py b/s3tests_boto3/functional/test_headers.py
index 557f234..360a2e6 100644
--- a/s3tests_boto3/functional/test_headers.py
+++ b/s3tests_boto3/functional/test_headers.py
@@ -1,5 +1,6 @@
 import boto3
 import pytest
+import botocore.config
 from botocore.exceptions import ClientError
 from email.utils import formatdate
 
@@ -209,7 +210,10 @@ def test_object_create_bad_contentlength_empty():
 @pytest.mark.auth_common
 @pytest.mark.fails_on_mod_proxy_fcgi
 def test_object_create_bad_contentlength_negative():
-    client = get_client()
+    # to test Content-Length=-1, we have to prevent the checksum calculation
+    # from switching to STREAMING-UNSIGNED-PAYLOAD-TRAILER
+    config = botocore.config.Config(request_checksum_calculation = 'when_required')
+    client = get_client(config)
     bucket_name = get_new_bucket()
     key_name = 'foo'
     e = assert_raises(ClientError, client.put_object, Bucket=bucket_name, Key=key_name, ContentLength=-1)