diff --git a/upload_package b/upload_package
index 5ac1b63..9f57dbe 100755
--- a/upload_package
+++ b/upload_package
@@ -54,13 +54,14 @@ PAYLOAD_SIZE=$(stat --format='%s' "${UPDATE_PATH}")
 PAYLOAD_SHA1=$(cat "${UPDATE_PATH}" | openssl dgst -sha1 -binary | base64)
 PAYLOAD_SHA256=$(cat "${UPDATE_PATH}" | openssl dgst -sha256 -binary | base64)
 
-sha256sum "${UPDATE_PATH}" > "${UPDATE_CHECKSUM_PATH}"
+(cd "${DATA_DIR}" && sha256sum "flatcar_production_update.gz") > "${UPDATE_CHECKSUM_PATH}"
 
 EXTRA_FILES=()
 EXTRA_SUMS=()
 shopt -s nullglob
 for EXTRA_FILE in "${DATA_DIR}/oem-"*.gz "${DATA_DIR}/flatcar-"*.gz; do
-  sha256sum "${EXTRA_FILE}" > "${EXTRA_FILE}.sha256"
+  BASENAME=$(basename "${EXTRA_FILE}")
+  (cd "${DATA_DIR}" && sha256sum "${BASENAME}") > "${EXTRA_FILE}.sha256"
   EXTRA_FILES+=("${EXTRA_FILE}")
   EXTRA_SUMS+=("${EXTRA_FILE}.sha256")
 done