diff --git a/lib/workers/pr/index.js b/lib/workers/pr/index.js
index <HASH>..<HASH> 100644
--- a/lib/workers/pr/index.js
+++ b/lib/workers/pr/index.js
@@ -175,6 +175,11 @@ async function ensurePr(prConfig) {
       /(https?:\/\/github.com\/[^/]*\/[^/]*\/(issues|pull)\/\w+)/g,
       '`$1`'
     );
+    logger.trace('Escaping links to GitHub users');
+    prBody = prBody.replace(
+      /]\(https?:\/\/github.com\/[a-z\d](?:[a-z\d]|-(?=[a-z\d])){0,38}\)/gi,
+      ']'
+    );
     // convert escaped backticks back to `
     const backTickRe = /&#x60;([^/]*?)&#x60;/g;
     prBody = prBody.replace(backTickRe, '`$1`');
fix: escape links to GitHub usernames