diff --git a/packaging/os/apt_repository.py b/packaging/os/apt_repository.py
index 8f6d18d09d5..a72c0505717 100644
--- a/packaging/os/apt_repository.py
+++ b/packaging/os/apt_repository.py
@@ -390,7 +390,7 @@ class UbuntuSourcesList(SourcesList):
                     continue
 
                 if source_line.startswith('ppa:'):
-                    source, ppa_owner, ppa_name = self._expand_ppa(i[3])
+                    source, ppa_owner, ppa_name = self._expand_ppa(source_line)
                     _repositories.append(source)
                 else:
                     _repositories.append(source_line)