diff --git a/extras/build-tests/nix/run-tests b/extras/build-tests/nix/run-tests
index 265739379..0471e9bd4 100755
--- a/extras/build-tests/nix/run-tests
+++ b/extras/build-tests/nix/run-tests
@@ -31,9 +31,10 @@ else
 	# (apparently there are mixed python psych .so versions)
 	rvm uninstall 2.5.3
 	rvm uninstall 2.4.5
-	rvm use system
+	#rvm use system
+	rvm reset
 	rvm list
-	apt-get install ruby-dev -y
+	sudo apt-get install ruby-dev -y
 	set -e
 	gem --version
 	gem install bundler -v "~>1.0"