diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7a3d0317..4d1a945b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -31,6 +31,7 @@ jobs:
         with:
           repository: 'YosysHQ/yosys'
           path: 'yosys'
+          submodules: true
 
       - name: Runtime environment
         run: |