diff --git a/test/backup.py b/test/backup.py
index 6a5173d2f2d..687ffcbeab7 100755
--- a/test/backup.py
+++ b/test/backup.py
@@ -38,6 +38,7 @@
 
 
 def setUpModule():
+  global xtrabackup_args
   xtrabackup_args = ['-backup_engine_implementation',
                    'xtrabackup',
                    '-xtrabackup_stream_mode',
diff --git a/test/xtrabackup_xtra.py b/test/xtrabackup_xtra.py
index f33dce89c60..bbf9fe1ed0e 100755
--- a/test/xtrabackup_xtra.py
+++ b/test/xtrabackup_xtra.py
@@ -39,6 +39,7 @@
 
 
 def setUpModule():
+  global xtrabackup_args
   xtrabackup_args = ['-backup_engine_implementation',
                    'xtrabackup',
                    '-xtrabackup_stream_mode',