diff --git a/lib/index.ts b/lib/index.ts
index 3e069af..4dc6061 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -401,7 +401,7 @@ class Sequence{
  *
  * 	1/2/4
  */
-export const getPattern = (str: string): string | undefined => {
+export const getPattern = (str: string): string => {
 	initialize();
 
 	str					= asciifold(str);