diff --git a/vagrant/provision.sh b/vagrant/provision.sh
index 7a31309..df35446 100755
--- a/vagrant/provision.sh
+++ b/vagrant/provision.sh
@@ -2,7 +2,7 @@
 
 PROJECT_NAME=$1
 
-PROJECT_DIR=/vagrant
+: ${PROJECT_DIR:=/vagrant}
 VIRTUALENV_DIR=/home/vagrant/.virtualenvs/$PROJECT_NAME
 
 PYTHON=$VIRTUALENV_DIR/bin/python