diff --git a/src/slovak/NumeralSlo.gf b/src/slovak/NumeralSlo.gf
index 96b2229fc..f96f8adc0 100644
--- a/src/slovak/NumeralSlo.gf
+++ b/src/slovak/NumeralSlo.gf
@@ -1,6 +1,6 @@
 concrete NumeralSlo of Numeral =
 
-  CatSlo **
+  CatSlo [Numeral,Digits] **
   
   open
     ResSlo,