diff --git a/.github/workflows/default_gems.yml b/.github/workflows/default_gems.yml
index 202adfc637bd8d..ea2e2870663e4f 100644
--- a/.github/workflows/default_gems.yml
+++ b/.github/workflows/default_gems.yml
@@ -17,6 +17,8 @@ jobs:
 
     runs-on: ubuntu-latest
 
+    if: ${{ github.repository == 'ruby/ruby' }}
+
     steps:
       - uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938 # v4.2.0
         with: