diff --git a/hgext/releasenotes.py b/hgext/releasenotes.py
--- a/hgext/releasenotes.py
+++ b/hgext/releasenotes.py
@@ -426,7 +426,7 @@
 
             lines.append('')
 
-    if lines[-1]:
+    if lines and lines[-1]:
         lines.append('')
 
     return '\n'.join(lines)