diff --git a/tests/test_web_sendfile_functional.py b/tests/test_web_sendfile_functional.py
index d77fe9b1e90..51c6a9de940 100644
--- a/tests/test_web_sendfile_functional.py
+++ b/tests/test_web_sendfile_functional.py
@@ -432,7 +432,7 @@ async def handler(request):
 
         body = await response.read()
         assert len(body) == 108, \
-            "failed 'bytes=61000-62000', received %d bytes" % len(body[0])
+            "failed 'bytes=61000-62000', received %d bytes" % len(body)
 
         assert content[61000:] == body