diff --git a/tests/modules/vpcs/test_vpcs_vm.py b/tests/modules/vpcs/test_vpcs_vm.py
index 3a0e811f..c16e10f0 100644
--- a/tests/modules/vpcs/test_vpcs_vm.py
+++ b/tests/modules/vpcs/test_vpcs_vm.py
@@ -202,8 +202,8 @@ def test_get_startup_script_using_default_script(vm):
     vm._script_file = None
 
     filepath = os.path.join(vm.working_dir, 'startup.vpc')
-    with open(filepath, 'w+') as f:
-        assert f.write(content)
+    with open(filepath, 'wb+') as f:
+        assert f.write(content.encode("utf-8"))
 
     assert vm.startup_script == content
     assert vm.script_file == filepath
diff --git a/tests/utils/test_asyncio.py b/tests/utils/test_asyncio.py
index 96fbde7b..b4fc7ae6 100644
--- a/tests/utils/test_asyncio.py
+++ b/tests/utils/test_asyncio.py
@@ -18,6 +18,7 @@
 
 import asyncio
 import pytest
+import sys
 from unittest.mock import MagicMock
 
 from gns3server.utils.asyncio import wait_run_in_executor, subprocess_check_output, wait_for_process_termination
@@ -43,6 +44,7 @@ def test_exception_wait_run_in_executor(loop):
         result = loop.run_until_complete(asyncio.async(exec))
 
 
+@pytest.mark.skipif(sys.platform.startswith("win"), reason="Not supported on Windows")
 def test_subprocess_check_output(loop, tmpdir, restore_original_path):
 
     path = str(tmpdir / "test")