diff --git a/library/init/lean/parser/token.lean b/library/init/lean/parser/token.lean
index 7f32549ae2..961b87c45e 100644
--- a/library/init/lean/parser/token.lean
+++ b/library/init/lean/parser/token.lean
@@ -28,9 +28,7 @@ private def finish_comment_block_aux : nat → nat → basic_parser_m unit
 | nesting (n+1) :=
   str "/-" *> finish_comment_block_aux (nesting + 1) n
   <|>
-  str "-/" *>
-  if nesting = 1 then pure ()
-  else finish_comment_block_aux (nesting - 1) n
+  str "-/" *> (if nesting = 1 then pure () else finish_comment_block_aux (nesting - 1) n)
   <|>
   any *> finish_comment_block_aux nesting n
 | _ _ := error "unreachable"