diff --git a/runtime/lua/vim/lsp/diagnostic.lua b/runtime/lua/vim/lsp/diagnostic.lua
index dcd54fd587..6f2f846a3b 100644
--- a/runtime/lua/vim/lsp/diagnostic.lua
+++ b/runtime/lua/vim/lsp/diagnostic.lua
@@ -1007,7 +1007,7 @@ function M.on_publish_diagnostics(_, _, params, client_id, _, config)
 
   local diagnostics = params.diagnostics
 
-  if if_nil(config.severity_sort, false) then
+  if config and if_nil(config.severity_sort, false) then
     table.sort(diagnostics, function(a, b) return a.severity > b.severity end)
   end