diff --git a/README.md b/README.md
index 35a1700..19c83ba 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ On Windows, you have to perform a `composer install` manually beforehand. Make s
 
 ### Dependency management
 
-`dev.sh` will download the `composer` package manager to the php archive file `composer.phar` and run it.
+`dev.sh` will ensure the git submodules have been pulled, then download the `composer` package manager to the php archive file `composer.phar` and run it.
 Composer will check for the php extension `pdo_sqlite` which must be enabled on your system. This usually includes installing a php-sqlite3 package and enabling it in /etc/php/php.ini:
 
     [PHP]
diff --git a/dev.sh b/dev.sh
index f716c23..a613267 100755
--- a/dev.sh
+++ b/dev.sh
@@ -8,6 +8,11 @@ test ! -e dataporten_config.php && cp -v dist/dataporten_config.php dataporten_c
 
 test -e composer.phar || curl -O https://getcomposer.org/composer.phar
 
+if test ! -f lib/OAuth2-Client/OAuth2Client.php ; then
+	echo Missing git submodules. Installing...
+	(set -x; git submodule update --init --recursive) || exit $?
+fi
+
 if test ! -d vendor; then
 	php composer.phar install || exit $?
 	cp -v dist/authsources_example.php vendor/simplesamlphp/simplesamlphp/config/authsources.php