diff --git a/main.js b/main.js
index 0d362716e..b50629004 100644
--- a/main.js
+++ b/main.js
@@ -10,6 +10,19 @@ let orig_win;
 let all_wins = [];
 let load_project_data;
 
+(() => {
+	// Allow advanced users to specify a custom userData directory.
+	// Useful for portable installations, and for setting up development environments.
+	const index = process.argv.findIndex(arg => arg === '--userData');
+	if (index !== -1) {
+		if (!process.argv.at(index + 1)) {
+			console.error('No path specified after --userData')
+			process.exit(1)
+		}
+		app.setPath('userData', process.argv[index + 1]);
+	}
+})()
+
 const LaunchSettings = {
 	path: path.join(app.getPath('userData'), 'launch_settings.json'),
 	settings: {},