diff --git a/src-modules/module/xcube/masken/21000_maskeninfo.unl b/src-modules/module/xcube/masken/21000_maskeninfo.unl
index a784315..4d1f1c2 100644
--- a/src-modules/module/xcube/masken/21000_maskeninfo.unl
+++ b/src-modules/module/xcube/masken/21000_maskeninfo.unl
@@ -33,7 +33,7 @@ and name=<<Ansicht in Ergebnisspalten>>]]>\
 </sqlvar>\
 <sqlvar name="nichtsicht_ergspalten" type='hashsequence'><![CDATA[\
 <#if coldef.is_sicht=0>\
-select distinct ${coldef.foreignkey_col} as apnr,\
+select distinct ${coldef.foreignkey_col}::varchar(255) as apnr,\
 ${coldef.foreignkey_cap} as name,\
 1::smallint as detailgesamtsort,\
 ${coldef.sortfield} as tmp_sortfield\