2 files changed, 2 insertions, 2 deletions

diff --git a/global.json b/global.json
index 6df1b3ab..4ec00563 100644
--- a/global.json
+++ b/global.json
@@ -1,6 +1,6 @@
 {
   "msbuild-sdks": {
-    "WixToolset.Sdk": "4.0.0-build-0206"
+    "WixToolset.Sdk": "4.0.0-build-0211"
   },
   "sdk": {
     "allowPrerelease": false
diff --git a/src/wixext/UIExtensionFactory.cs b/src/wixext/UIExtensionFactory.cs
index 1c9caacc..141aa39f 100644
--- a/src/wixext/UIExtensionFactory.cs
+++ b/src/wixext/UIExtensionFactory.cs
@@ -8,7 +8,7 @@ namespace WixToolset.UI
 
     public class UIExtensionFactory : BaseExtensionFactory
     {
-        protected override IEnumerable<Type> ExtensionTypes => new[]
+        protected override IReadOnlyCollection<Type> ExtensionTypes => new[]
         {
             typeof(UIExtensionData),
         };