diff --git a/vlib/v/scanner/scanner.v b/vlib/v/scanner/scanner.v
index d7fb9c0ea7..8b67cf9d89 100644
--- a/vlib/v/scanner/scanner.v
+++ b/vlib/v/scanner/scanner.v
@@ -994,8 +994,9 @@ fn (s Scanner) line(n int) string {
 	return res.trim_right('\r\n').trim_left('\r\n')
 }
 
+[inline]
 fn is_name_char(c byte) bool {
-	return c == `_` || c.is_letter()
+	return (c >= `a` && c <= `z`) || (c >= `A` && c <= `Z`) || c == `_`
 }
 
 [inline]