diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0f4297bd..96515960 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -15,10 +15,10 @@ on:
 jobs:
   test-nutshell:
     # The type of runner that the job will run on
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Prepare environment
         run: |
diff --git a/difftest b/difftest
index c626933d..9af8b1ed 160000
--- a/difftest
+++ b/difftest
@@ -1 +1 @@
-Subproject commit c626933daedfa21547010917ddb5eb284fce72b6
+Subproject commit 9af8b1ed4b39b9e325a483c9016005b5c692c8f5