diff --git a/.github/workflows/rfc-check.yml b/.github/workflows/rfc-check.yml
index a975ece..6001587 100644
--- a/.github/workflows/rfc-check.yml
+++ b/.github/workflows/rfc-check.yml
@@ -21,9 +21,10 @@ jobs:
       - uses: actions/checkout@v4
       - name: dependencies
         run: |
-          sudo apt-get install -y aspell cmake python3 python3-pip python3-setuptools python3-wheel cargo xmlstarlet
+          sudo apt-get install -y aspell cmake python3 python3-pip python3-setuptools python3-wheel ruby cargo xmlstarlet
           sudo pip3 install --upgrade pip
           sudo pip3 install xml2rfc abnf
+	  sudo gem install cbor-diag
           cargo install cddl
       - name: xml2rfc
         run: |