diff --git a/.kokoro/build-with-run.sh b/.kokoro/build-with-run.sh
index 949ac6d253..b8a6716b6e 100755
--- a/.kokoro/build-with-run.sh
+++ b/.kokoro/build-with-run.sh
@@ -33,7 +33,9 @@ gcloud config set project $GOOGLE_CLOUD_PROJECT
 # to run them concurrently.
 export SAMPLE_VERSION="${KOKORO_GIT_COMMIT:-latest}"
 export SAMPLE_NAME="$(basename $(pwd))"
-export SERVICE_NAME="${SAMPLE_NAME}-${KOKORO_GITHUB_PULL_REQUEST_NUMBER}"
+# Builds not triggered by a PR will fall back to the commit hash then "latest".
+SUFFIX=${KOKORO_GITHUB_PULL_REQUEST_NUMBER:-${SAMPLE_VERSION:0:12}}
+export SERVICE_NAME="${SAMPLE_NAME}-${SUFFIX}"
 export CONTAINER_IMAGE="gcr.io/${GOOGLE_CLOUD_PROJECT}/run-${SAMPLE_NAME}:${SAMPLE_VERSION}"
 
 # Register post-test cleanup.