diff --git a/Bigop.lean b/Bigop.lean
index eb575a9..5adf4ec 100644
--- a/Bigop.lean
+++ b/Bigop.lean
@@ -116,7 +116,7 @@ syntax "def_bigop" str term:max term:max : command
 -- `F` is inserted only in the second expansion, the expansion of the new macro `$head`.
 macro_rules
   | `(def_bigop $head $op $unit) =>
-    `(macro $head:strLit "(" idx:index ")" F:term : term => `(\big_ [$op, $unit] ($$idx) $$F))
+    `(macro $head:str "(" idx:index ")" F:term : term => `(\big_ [$op, $unit] ($$idx) $$F))
 
 def_bigop "SUM" Nat.add 0
 #check SUM (i <- [0, 1, 2]) i+1
diff --git a/Expander.lean b/Expander.lean
index 8d71e3d..4732a3b 100644
--- a/Expander.lean
+++ b/Expander.lean
@@ -124,8 +124,8 @@ partial def expand : Syntax → ExpanderM Syntax
   | `(fun $id:ident => $e) => do
     let e ← withLocal (getIdentVal id) (expand e)
     `(fun $id:ident => $e)
-  | `($num:numLit) => `($num:numLit)
-  | `($str:strLit) => `($str:strLit)
+  | `($num:num) => `($num:num)
+  | `($str:str) => `($str:str)
   | `($n:quotedName) => `($n:quotedName)
   | `($fn $args*) => do
     let fn ← expand fn
@@ -195,8 +195,8 @@ partial def pp : Syntax → Format
     | ps => ppIdent id.getId ++ bracket "{" (joinSep (ps.map (format ∘ Prod.fst)) ", ") "}"
   | `(fun ($id : $ty) => $e) => paren f!"fun {paren (pp id ++ " : " ++ pp ty)} => {pp e}"
   | `(fun $id => $e) => paren f!"fun {pp id} => {pp e}"
-  | `($num:numLit) => format (num.isNatLit?.getD 0)
-  | `($str:strLit) => repr (str.isStrLit?.getD "")
+  | `($num:num) => format (num.isNatLit?.getD 0)
+  | `($str:str) => repr (str.isStrLit?.getD "")
   | `($fn $args*) => paren <| pp fn ++ " " ++ joinSep (args.toList.map pp) line
   | `(def $id:ident := $e) => f!"def {ppIdent id.getId} := {pp e}"
   | `(syntax $[(name := $n)]? $[(priority := $prio)]? $[$args:stx]* : $kind) => "syntax ..."  -- irrelevant for this example
diff --git a/lean-toolchain b/lean-toolchain
index a992958..3a406d1 100644
--- a/lean-toolchain
+++ b/lean-toolchain
@@ -1 +1 @@
-leanprover/lean4:nightly-2022-02-05
+leanprover/lean4:nightly-2022-04-02