Correct

指不定

/ zhǐ bùdìng / 
Strokes

Example

As an Adverb

perhaps; maybe

1
Nǐ
你
béng
甭
děng
等
tā
他
le
了
  
,
tā
他
zhǐbùdìng
指不定
lái
来
bù
不
lái
来
ne
呢
  
。

Don't wait for him; maybe he isn't coming.