diff --git a/vlib/v/parser/containers.v b/vlib/v/parser/containers.v
index 92778ab254..9dddfb60b6 100644
--- a/vlib/v/parser/containers.v
+++ b/vlib/v/parser/containers.v
@@ -94,7 +94,9 @@ fn (mut p Parser) array_init() ast.ArrayInit {
 		}
 	}
 	if exprs.len == 0 && p.tok.kind != .lcbr && has_type {
-		p.warn_with_pos('use `x := []Type{}` instead of `x := []Type`', first_pos.extend(last_pos))
+		if !p.pref.is_fmt {
+			p.warn_with_pos('use `x := []Type{}` instead of `x := []Type`', first_pos.extend(last_pos))
+		}
 	}
 	mut has_len := false
 	mut has_cap := false
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index df1b06a1e1..197f929d82 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -665,7 +665,9 @@ fn (mut p Parser) fn_args() ([]table.Param, bool, bool) {
 			}
 			if p.tok.kind == .key_mut {
 				// TODO remove old syntax
-				p.warn_with_pos('use `mut f Foo` instead of `f mut Foo`', p.tok.position())
+				if !p.pref.is_fmt {
+					p.warn_with_pos('use `mut f Foo` instead of `f mut Foo`', p.tok.position())
+				}
 				is_mut = true
 			}
 			if p.tok.kind == .ellipsis {