diff --git a/src/BizHawk.Client.EmuHawk/MainForm.Events.cs b/src/BizHawk.Client.EmuHawk/MainForm.Events.cs
index ae66c47f0c..6aa7b48301 100644
--- a/src/BizHawk.Client.EmuHawk/MainForm.Events.cs
+++ b/src/BizHawk.Client.EmuHawk/MainForm.Events.cs
@@ -932,7 +932,7 @@ namespace BizHawk.Client.EmuHawk
 
 		private void FileExtensionsMenuItem_Click(object sender, EventArgs e)
 		{
-			using var form = new FileExtensionPreferences(Config);
+			using var form = new FileExtensionPreferences(Config.PreferredPlatformsForExtensions);
 			var result = form.ShowDialog();
 			AddOnScreenMessage(result.IsOk()
 				? "Rom Extension Preferences changed"
diff --git a/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferences.cs b/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferences.cs
index b8a15cef9d..f83e5ab365 100644
--- a/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferences.cs
+++ b/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferences.cs
@@ -1,19 +1,18 @@
 using System;
+using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
 using System.Windows.Forms;
 
-using BizHawk.Client.Common;
-
 namespace BizHawk.Client.EmuHawk
 {
 	public partial class FileExtensionPreferences : Form
 	{
-		private readonly Config _config;
+		private readonly IDictionary<string, string> _preferredPlatformsForExtensions;
 
-		public FileExtensionPreferences(Config config)
+		public FileExtensionPreferences(IDictionary<string, string> preferredPlatformsForExtensions)
 		{
-			_config = config;
+			_preferredPlatformsForExtensions = preferredPlatformsForExtensions;
 			InitializeComponent();
 		}
 
@@ -21,9 +20,9 @@ namespace BizHawk.Client.EmuHawk
 		{
 			int spacing = UIHelper.ScaleY(30);
 			int count = 0;
-			foreach (var kvp in _config.PreferredPlatformsForExtensions)
+			foreach (var kvp in _preferredPlatformsForExtensions)
 			{
-				var picker = new FileExtensionPreferencesPicker
+				var picker = new FileExtensionPreferencesPicker(_preferredPlatformsForExtensions)
 				{
 					FileExtension = kvp.Key,
 					OriginalPreference = kvp.Value,
@@ -39,9 +38,10 @@ namespace BizHawk.Client.EmuHawk
 		{
 			foreach (var picker in PrefPanel.Controls.OfType<FileExtensionPreferencesPicker>())
 			{
-				_config.PreferredPlatformsForExtensions[picker.FileExtension] = picker.CurrentlySelectedSystemId;
+				_preferredPlatformsForExtensions[picker.FileExtension] = picker.CurrentlySelectedSystemId;
 			}
 
+			DialogResult = DialogResult.OK;
 			Close();
 		}
 
diff --git a/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferencesPicker.cs b/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferencesPicker.cs
index 8b6eb14a13..55f6d4ad18 100644
--- a/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferencesPicker.cs
+++ b/src/BizHawk.Client.EmuHawk/config/FileExtensionPreferencesPicker.cs
@@ -9,10 +9,13 @@ namespace BizHawk.Client.EmuHawk
 {
 	public partial class FileExtensionPreferencesPicker : UserControl
 	{
-		public FileExtensionPreferencesPicker()
+		private IDictionary<string, string> _preferredPlatformsForExtensions;
+
+		public FileExtensionPreferencesPicker(IDictionary<string, string> preferredPlatformsForExtensions)
 		{
-			InitializeComponent();
+			_preferredPlatformsForExtensions = preferredPlatformsForExtensions;
 			_availableSystems = new SystemLookup().AllSystems.ToList();
+			InitializeComponent();
 		}
 
 		private readonly List<SystemLookup.SystemInfo> _availableSystems;
@@ -47,14 +50,14 @@ namespace BizHawk.Client.EmuHawk
 		{
 			PopulatePlatforms();
 
-			var selectedSystemId = GlobalWin.Config.PreferredPlatformsForExtensions[FileExtension];
+			var selectedSystemId = _preferredPlatformsForExtensions[FileExtension];
 			if (!string.IsNullOrEmpty(selectedSystemId))
 			{
 				var selectedSystem = _availableSystems.FirstOrDefault(s => s.SystemId == selectedSystemId);
 
 				var selectedItem = PlatformDropdown.Items
 					.OfType<string>()
-					.FirstOrDefault(item => item == (selectedSystem != null ? selectedSystem.FullName : ""));
+					.FirstOrDefault(item => item == (selectedSystem?.FullName ?? ""));
 
 				if (selectedItem != null)
 				{