diff --git a/lib/platform/github/index.js b/lib/platform/github/index.js
index <HASH>..<HASH> 100644
--- a/lib/platform/github/index.js
+++ b/lib/platform/github/index.js
@@ -1063,8 +1063,9 @@ async function getOpenPrs() {
         } else {
           const baseCommitSHA = await getBaseCommitSHA();
           if (
+            pr.commits.nodes[0].commit.parents.edges.length &&
             pr.commits.nodes[0].commit.parents.edges[0].node.oid !==
-            baseCommitSHA
+              baseCommitSHA
           ) {
             pr.isStale = true;
           }
fix(github): check for parent edges