diff --git a/modules/lang/csharp/packages.el b/modules/lang/csharp/packages.el
index 9731635b9..2a5441da5 100644
--- a/modules/lang/csharp/packages.el
+++ b/modules/lang/csharp/packages.el
@@ -1,7 +1,10 @@
 ;; -*- no-byte-compile: t; -*-
 ;;; lang/csharp/packages.el
 
-(package! csharp-mode :pin "856ecbc0a78ae3bdc2db2ae4d16be43e2d9d9c5e")
+(package! csharp-mode
+  :pin "856ecbc0a78ae3bdc2db2ae4d16be43e2d9d9c5e"
+  :built-in 'prefer)  ; Built-in as of Emacs 29
+
 (package! csproj-mode :pin "a7f0f4610c976a28c41b9b8299892f88b5d0336c")
 (package! sln-mode :pin "0f91d1b957c7d2a7bab9278ec57b54d57f1dbd9c")
 ;; sln-mode depends on font-lock-ext