diff --git a/lib/proton.dart b/lib/proton.dart
index 28288ff..2ae5e01 100644
--- a/lib/proton.dart
+++ b/lib/proton.dart
@@ -24,7 +24,7 @@ class ProtonState extends State<Proton> {
     }
     await dir.create(recursive: true);
 
-    Map<String, String> env = Platform.environment;
+    Map<String, String> env = Map.from(Platform.environment);
     env["STEAM_COMPAT_CLIENT_INSTALL_PATH"] = "~/.steam";
     env["STEAM_COMPAT_DATA_PATH"] = dir.path;