Do you always make this mistake?

Here's a quick note before I hit the sack.

• hit the sack 床に就く◆【直訳】綿の入った袋(sack)（＝マットレス）に自分の体をぶつける(hit)
• Last night, I hit the sack before midnight. : 昨夜は夜中の12時前に床に就いた。(definition from 英辞郎 on the web)
  

The word "mistake" should usually be used as a noun, not a verb. The verb you should use with "mistake" is "make".

• × I always mistake.
• ○ I always make that kind of mistake.

We use "mistake" as a verb like this:

• 見誤る (みあやまる) (v5r,vt) to mistake someone for someone else; to misread; (definition from Edict)
  

• I mistook you for someone I know.
• He mistook one corner for the next one, and that's how he got lost.
• It's easy to mistake one twin for the other one.
  

Kusanagi probably feels like he made a mistake. I've been writing a program all week, and it has taken a long time because I keep making a lot of mistakes. If I make a Japanese mistake, please let me know.