diff --git a/lib/tokenize-arg-string.ts b/lib/tokenize-arg-string.ts
index 97da020f..52827080 100644
--- a/lib/tokenize-arg-string.ts
+++ b/lib/tokenize-arg-string.ts
@@ -4,7 +4,7 @@ export function tokenizeArgString (argString: string | any[]): string[] {
     return argString.map(e => typeof e !== 'string' ? e + '' : e)
   }
 
-  argString = (argString as string).trim()
+  argString = argString.trim()
 
   let i = 0
   let prevC: string | null = null