[Exim] $spam_score_int floating point error?

I'm using exiscan to reject messages with a spam score over 4.5.

  deny condition = ${if <{$message_size}{MAX_SCAN_SIZE}{1}{0}}
      spam = nobody:true
      condition = ${if >{$spam_score_int}{45}{1}{0}}

Sometimes, a message with a score of 4.6 will get through. 4.7 and
above always seems to get blocked, so I'm guessing that when $spam_score
is 4.6, $spam_score_int is sometimes 45 rather than 46.
Has anyone else noticed this behaviour?

xn