diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 10b4b2b832a..d3a1c23105f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -166,9 +166,7 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Deepen cloned repo
-        env:
-          BASE_SHA: ${{ github.event.pull_request.base.sha }}
-        run: 'git fetch --depth=1 origin $BASE_SHA:refs/tags/BASE'
+        run: 'git fetch --depth=1 origin ${{ github.base_ref }}:refs/tags/BASE'
 
       - name: Setup Node.js
         uses: actions/setup-node@v2
@@ -191,9 +189,7 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Deepen cloned repo
-        env:
-          BASE_SHA: ${{ github.event.pull_request.base.sha }}
-        run: 'git fetch --depth=1 origin $BASE_SHA:refs/tags/BASE'
+        run: 'git fetch --depth=1 origin ${{ github.base_ref }}:refs/tags/BASE'
 
       - name: Setup Node.js
         uses: actions/setup-node@v2