diff --git a/lexer.go b/lexer.go
index 3c7641a..bd23665 100644
--- a/lexer.go
+++ b/lexer.go
@@ -591,7 +591,7 @@
 }
 
 func init() {
-	dateRegexp = regexp.MustCompile("^\\d{1,4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(\\.\\d{1,9})?(Z|[+-]\\d{2}:\\d{2})")
+	dateRegexp = regexp.MustCompile(`^\d{1,4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d{1,9})?(Z|[+-]\d{2}:\d{2})`)
 }
 
 // Entry point
diff --git a/querylexer.go b/querylexer.go
index 1532e1d..61153cb 100644
--- a/querylexer.go
+++ b/querylexer.go
@@ -105,7 +105,7 @@
 }
 
 func (l *queryLexer) accept(valid string) bool {
-	if strings.IndexRune(valid, l.next()) >= 0 {
+	if strings.ContainsRune(valid, l.next()) {
 		return true
 	}
 	l.backup()