Error on setting the Mysql_config environment variable

I'm trying to install this database driver for Node.js, for which I'm supposed to specify the MYSQL_CONFIG environment variable through

$ export MYSQL_CONFIG=/usr/local/mysql/bin/mysql_config

prior to running $ npm install db-mysql but I'm getting this error in the terminal.

bash: export: `=': not a valid identifier
bash: export: `/usr/bin/mysql_config': not a valid identifier

I don't get what's going on. Please help!