diff --git a/lib/platform/github/index.js b/lib/platform/github/index.js
index 6aca9bd4e3e0c5b8c5a538b19fe4a586083662e0..6281afa50bbbc3a4a7960f64db71801f55e84f31 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;
           }