diff --git a/doc/ruby-best-practices/ruby-best-practices.SlackBuild b/doc/ruby-best-practices/ruby-best-practices.SlackBuild
index 6cf763df..70cdbdd9 100755
--- a/doc/ruby-best-practices/ruby-best-practices.SlackBuild
+++ b/doc/ruby-best-practices/ruby-best-practices.SlackBuild
@@ -21,7 +21,7 @@ PREFIX=/usr
 rm -fr $PKG
 
 # get sources
-[ -e $REPOSITORY ] && git clone http://github.com/sandal/rbp-book.git $REPOSITORY
+[ ! -e $REPOSITORY ] && git clone http://github.com/sandal/rbp-book.git $REPOSITORY
 ( cd $REPOSITORY && git pull )
 VERSION="$( cd $REPOSITORY && git log -1 --format=%h_%ad --date=format:%Y.%m.%d )"