diff --git a/lib/datasource/docker/index.js b/lib/datasource/docker/index.js
index 7b9a2a44f10a40..00b1d5898e9771 100644
--- a/lib/datasource/docker/index.js
+++ b/lib/datasource/docker/index.js
@@ -381,12 +381,12 @@ async function getLabels(registry, repository, tag) {
     }
     const manifest = JSON.parse(manifestResponse.body);
     let labels = {};
-    const configDigest = manifest.config.digest;
     // istanbul ignore if
     if (!manifest.config) {
       logger.warn({ manifest }, 'Docker manifest error: no config');
       throw new Error('registry-failure');
     }
+    const configDigest = manifest.config.digest;
     const headers = await getAuthHeaders(registry, repository);
     if (!headers) {
       logger.info('No docker auth found - returning');