diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index 97c37be6a6767..b6ee2969559fa 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -12,6 +12,9 @@
     // Uncomment next line if you have devcontainer.env
     // "--env-file=.devcontainer/devcontainer.env"
   ],
+  "containerEnv": {
+    "ENVOY_SRCDIR": "${containerWorkspaceFolder}",
+  },
   "settings": {
     "terminal.integrated.shell.linux": "/bin/bash",
     "bazel.buildifierFixOnFormat": true,
diff --git a/ci/run_clang_tidy.sh b/ci/run_clang_tidy.sh
index fe5d5fdd20478..b29a624c3f453 100755
--- a/ci/run_clang_tidy.sh
+++ b/ci/run_clang_tidy.sh
@@ -113,9 +113,7 @@ elif [[ "${RUN_FULL_CLANG_TIDY}" == 1 ]]; then
   run_clang_tidy
 else
   if [[ -z "${DIFF_REF}" ]]; then
-    if [[ "${BUILD_REASON}" == "PullRequest" ]]; then
-      DIFF_REF="remotes/origin/${SYSTEM_PULLREQUEST_TARGETBRANCH}"
-    elif [[ "${BUILD_REASON}" == *CI ]]; then
+    if [[ "${BUILD_REASON}" == *CI ]]; then
       DIFF_REF="HEAD^"
     else
       DIFF_REF=$("${ENVOY_SRCDIR}"/tools/git/last_github_commit.sh)
diff --git a/ci/run_envoy_docker.sh b/ci/run_envoy_docker.sh
index e0f204e67fcfa..da5115db52747 100755
--- a/ci/run_envoy_docker.sh
+++ b/ci/run_envoy_docker.sh
@@ -83,7 +83,6 @@ docker run --rm \
        -e ENVOY_BUILD_IMAGE \
        -e ENVOY_SRCDIR \
        -e ENVOY_BUILD_TARGET \
-       -e SYSTEM_PULLREQUEST_TARGETBRANCH \
        -e SYSTEM_PULLREQUEST_PULLREQUESTNUMBER \
        -e GCS_ARTIFACT_BUCKET \
        -e GITHUB_TOKEN \