diff --git a/lib/workers/pr/code-owners.ts b/lib/workers/pr/code-owners.ts
index b7062a740229deeb36d392ce9c58360067245e23..1f5090e39d28fde1a7837a873e57ae4b3a9a87f0 100644
--- a/lib/workers/pr/code-owners.ts
+++ b/lib/workers/pr/code-owners.ts
@@ -31,7 +31,7 @@ export async function codeOwnersForPr(pr: Pr): Promise<string[]> {
       })
       .reverse();
 
-    const matchingRule = rules.find((rule) => prFiles.every(rule.match));
+    const matchingRule = rules.find((rule) => prFiles?.every(rule.match));
     if (!matchingRule) {
       return [];
     }