diff --git a/lib/pronto/github.rb b/lib/pronto/github.rb
index 72b6cef2..e8b1aa6a 100644
--- a/lib/pronto/github.rb
+++ b/lib/pronto/github.rb
@@ -102,6 +102,8 @@ def pull_id
 
     def pull_sha
       pull[:head][:sha] if pull
+    rescue Pronto::Error
+      nil
     end
 
     def pull