diff --git a/bauh/commons/system.py b/bauh/commons/system.py
index 795d85a0..bbab5e09 100644
--- a/bauh/commons/system.py
+++ b/bauh/commons/system.py
@@ -96,8 +96,7 @@ class SimpleProcess:
 
         if extra_env:
             for var, val in extra_env.items():
-                if var not in env:
-                    env[var] = val
+                env[var] = val
 
         args = {
             "stdout": subprocess.PIPE,
diff --git a/bauh/gems/web/nativefier.py b/bauh/gems/web/nativefier.py
index e6fcd215..afd91fa6 100644
--- a/bauh/gems/web/nativefier.py
+++ b/bauh/gems/web/nativefier.py
@@ -20,8 +20,9 @@ def install(url: str, name: str, output_dir: str, electron_version: Optional[str
     if extra_options:
         cmd.extend(extra_options)
 
+    extra_env = {'XDG_CACHE_HOME': os.path.dirname(ELECTRON_CACHE_DIR)} if not os.getenv('XDG_CACHE_HOME') else None
     return SimpleProcess(cmd, cwd=cwd, extra_paths=NODE_PATHS if not system else None,
-                         extra_env={'XDG_CACHE_HOME': os.path.dirname(ELECTRON_CACHE_DIR)})
+                         extra_env=extra_env)
 
 
 def is_available() -> bool: