diff --git a/test/cluster-py/master.lua b/test/cluster-py/master.lua
index e924b549..b43bafd5 100644
--- a/test/cluster-py/master.lua
+++ b/test/cluster-py/master.lua
@@ -1,5 +1,5 @@
 #!/usr/bin/env tarantool
-os = require('os')
+local os = require('os')
 box.cfg({
     listen              = os.getenv("LISTEN"),
     memtx_memory        = 107374182,
diff --git a/unit/suites/box.lua b/unit/suites/box.lua
index 6bf82606..92114a8e 100644
--- a/unit/suites/box.lua
+++ b/unit/suites/box.lua
@@ -1,5 +1,5 @@
 #!/usr/bin/env tarantool
-os = require('os')
+local os = require('os')
 
 require('console').listen(os.getenv("ADMIN_PORT"))
 box.cfg{