diff --git a/.github/workflows/bazel.yml b/.github/workflows/bazel.yml
index a608806abe760..41a7d14e0a51d 100644
--- a/.github/workflows/bazel.yml
+++ b/.github/workflows/bazel.yml
@@ -133,9 +133,6 @@ jobs:
           ref: ${{ inputs.ref || github.ref }}
           fetch-depth: ${{ steps.depth.outputs.val }}
           fetch-tags: ${{ inputs.fetch-depth != '' }}
-      - name: Fetch base ref for PR comparison
-        if: github.event.pull_request.base.sha
-        run: git fetch --depth=1 origin ${{ github.event.pull_request.base.sha }}
       - name: Pull latest changes from head ref for PRs
         if: contains(github.head_ref, 'renovate/')
         run: git pull origin "$HEAD_REF"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8013d3720cac8..1706d11ce2702 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -39,10 +39,13 @@ jobs:
           echo "Running all targets for ${{ github.event_name }} event"
           echo "//java/... //py:all //rb/... //dotnet/... //rust/..." > bazel-targets.txt
         else
-          BASE_SHA="${{ github.event.pull_request.base.sha || github.event.before }}"
-          HEAD_SHA="${{ github.event.pull_request.head.sha || 'HEAD' }}"
+          if [ -n "${{ github.event.pull_request.base.sha }}" ]; then
+            BASE_SHA="HEAD^1"
+          else
+            BASE_SHA="${{ github.event.before }}"
+          fi
           if [ -n "$BASE_SHA" ]; then
-            ./go bazel:affected_targets "${BASE_SHA}..${HEAD_SHA}" bazel-test-file-index
+            ./go bazel:affected_targets "${BASE_SHA}..HEAD" bazel-test-file-index
           else
             ./go bazel:affected_targets bazel-test-file-index
           fi