diff --git a/doc/release/contribs.py b/doc/release/contribs.py
index c0a34e6eb4a..18a108e37a5 100755
--- a/doc/release/contribs.py
+++ b/doc/release/contribs.py
@@ -42,7 +42,8 @@ def call(cmd):
 
 def key(author):
     author = [v for v in author.split() if v[0] in string.ascii_letters]
-    return author[-1]
+    if len(author) > 0:
+        return author[-1]
 
 authors = sorted(set(authors), key=key)