diff --git a/extras/build-tests/nix/run-tests b/extras/build-tests/nix/run-tests
index 6ac6ffb8d..d1dbca5ef 100755
--- a/extras/build-tests/nix/run-tests
+++ b/extras/build-tests/nix/run-tests
@@ -29,9 +29,7 @@ else
 	gem --version
 	# And an attempt to fix things on Travis-CI
 	# (apparently there are mixed python psych .so versions)
-	gem uninstall psych
-	gem update --system
-
+	rvm uninstall 2.3.8
 	set -e
 
 	gem install bundler -v "~>1.0"