diff --git a/odoo_openupgrade_wizard/cli_build.py b/odoo_openupgrade_wizard/cli_build.py
index 443e0cf..7b1c242 100644
--- a/odoo_openupgrade_wizard/cli_build.py
+++ b/odoo_openupgrade_wizard/cli_build.py
@@ -4,6 +4,7 @@ from odoo_openupgrade_wizard.configuration_version_dependant import (
     _get_repo_file,
 )
 from odoo_openupgrade_wizard.tools_system import (
+    create_virtualenv,
     ensure_folder_exists,
     git_aggregate,
 )
@@ -24,5 +25,8 @@ def build(ctx):
         # 1. Create main folder for the odoo version
         ensure_folder_exists(step["local_path"], mode="777")
 
-        # 2. gitaggregate source code
+        # 2. Create virtual environment
+        create_virtualenv(step["local_path"], step["python"])
+
+        # 3. gitaggregate source code
         git_aggregate(step["local_path"], _get_repo_file(ctx, step))
diff --git a/odoo_openupgrade_wizard/tools_system.py b/odoo_openupgrade_wizard/tools_system.py
index c6cf402..c8b91b4 100644
--- a/odoo_openupgrade_wizard/tools_system.py
+++ b/odoo_openupgrade_wizard/tools_system.py
@@ -1,10 +1,12 @@
 import argparse
 import os
+import subprocess
 
 from git_aggregator import main as gitaggregate_cmd
 from git_aggregator.utils import working_directory_keeper
 from jinja2 import Template
 from loguru import logger
+from plumbum import local
 from plumbum.cmd import mkdir
 
 
@@ -63,3 +65,18 @@ def git_aggregate(folder_path, config_path):
             % config_path
         )
         gitaggregate_cmd.run(args)
+
+
+def create_virtualenv(folder_path, python_version):
+    """
+    Create a virtual env named ``env`` in the ``folder_path`` folder
+    with the given ``python_version``.
+    """
+    with local.cwd(folder_path):
+        logger.info(
+            "Create Virtual Env in %s with version %s"
+            % (folder_path, python_version)
+        )
+        subprocess.check_output(
+            ["virtualenv", "env", "--python", python_version]
+        )
diff --git a/pytest.ini b/pytest.ini
index b9a229e..4c83c3a 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -1,2 +1,2 @@
 [pytest]
-norecursedirs = output/*
\ No newline at end of file
+norecursedirs = output/*
diff --git a/tests/cli_build_test.py b/tests/cli_build_test.py
index 8df85d7..b030199 100644
--- a/tests/cli_build_test.py
+++ b/tests/cli_build_test.py
@@ -1,4 +1,3 @@
-import filecmp
 from pathlib import Path
 
 from click.testing import CliRunner
@@ -9,10 +8,10 @@ from odoo_openupgrade_wizard.cli import main
 
 def test_cli_build():
     output_folder_path = Path("./tests/output")
-    expected_folder_path = Path("./tests/output_expected")
     mkdir([output_folder_path, "--parents"])
 
-    # We initialize an env with only one version to avoid to git clone large data
+    # We initialize an env with only one version to avoid to git clone
+    # large data
     CliRunner().invoke(
         main,
         [