diff --git a/petl/io/xlsx.py b/petl/io/xlsx.py
index f059b69d..a960c7a1 100644
--- a/petl/io/xlsx.py
+++ b/petl/io/xlsx.py
@@ -131,7 +131,7 @@ def _load_or_create_workbook(filename, mode, sheet):
 
     import openpyxl
     wb = None
-    if mode != "overwrite" and (mode != "replace" or sheet is not None):
+    if not (mode == "overwrite" or (mode == "replace" and sheet is None)):
         try:
             source = read_source_from_arg(filename)
             with source.open('rb') as source2:
diff --git a/petl/test/io/test_remotes.py b/petl/test/io/test_remotes.py
index 504b39f9..bcbdb9db 100644
--- a/petl/test/io/test_remotes.py
+++ b/petl/test/io/test_remotes.py
@@ -3,7 +3,6 @@
 
 import sys
 import os
-import time
 from importlib import import_module
 
 from petl.compat import PY3