Bash misinterpreting lenght of PS1 when using ANSI escape sequences

if i use the following

export PS1='\033[36m$ \033[0m'

Bash misunderstands the length of the prompt and starts line-wrapping too early. My assumption was that it is counting every character, but comparing ${#PS1} to $COLUMNS shows that not to be the case. if i instead use the following

export PS1='$ '

there is no issue additionally, if i use dash shell, this does not happen, so i know it is an issue with Bash, and not my terminal etc. however, if i launch dash in vi mode with dash -V or set -o vi, the escape characters are ignored and not sent to my terminal at all. I assume this is a bug in dash though, so i reported this on the dash mailing list. thanks