diff --git a/runtime/spell/pt/main.aap b/runtime/spell/pt/main.aap
index 3d08faf..751fb95 100644
--- a/runtime/spell/pt/main.aap
+++ b/runtime/spell/pt/main.aap
@@ -29,7 +29,7 @@
         ../README_pt.txt
 
 $SPELLDIR/pt.latin1.spl : $FILES
-        :sys env LANG=pt_PT.ISO8859-1 LC_ALL=pt_PT.ISO8859-1
+        :sys env LANG=pt_PT.ISO-8859-1 LC_ALL=pt_PT.ISO-8859-1
 		$VIM -u NONE -e -c "mkspell! $SPELLDIR/pt pt_PT pt_BR" -c q
 
 $SPELLDIR/pt.utf-8.spl : $FILES