diff --git a/script/ci-install-compiler b/script/ci-install-compiler
index 3a68b3a39..0727d7232 100755
--- a/script/ci-install-compiler
+++ b/script/ci-install-compiler
@@ -2,5 +2,6 @@
 
 gem install minitest
 gem install minitap
+gem install hrx
 
 pip2 install --user 'requests[security]'