diff --git a/cave_data/1623-21.html b/cave_data/1623-21.html
index b344af029..0e6d3582a 100644
--- a/cave_data/1623-21.html
+++ b/cave_data/1623-21.html
@@ -27,7 +27,7 @@ the form documented at
 
 <entrance>
   <entranceslug>1623-21</entranceslug>
-  <letter></letter>
+  <letter>a</letter>
 </entrance>
 
 <explorers>H&ouml;hlenforschervereinigung Altaussee, 1938</explorers>