diff --git a/src/Lean/Data/Lsp/Workspace.lean b/src/Lean/Data/Lsp/Workspace.lean
index 8f22f920fc..dcf7e3ec37 100644
--- a/src/Lean/Data/Lsp/Workspace.lean
+++ b/src/Lean/Data/Lsp/Workspace.lean
@@ -29,7 +29,7 @@ structure WorkspaceFolder where
 
 structure FileSystemWatcher where
   globPattern : String
-  kind : Option Nat := none
+  kind? : Option Nat := none
   deriving FromJson, ToJson
 
 namespace FileSystemWatcher