diff --git a/MagicHaskeller.cabal b/MagicHaskeller.cabal
--- a/MagicHaskeller.cabal
+++ b/MagicHaskeller.cabal
@@ -1,5 +1,5 @@
 Name:            MagicHaskeller
-Version:         0.9.6.4.4
+Version:         0.9.6.4.5
 Cabal-Version:   >= 1.8
 License:         BSD3
 License-file:	 LICENSE 
diff --git a/MagicHaskeller/CoreLang.lhs b/MagicHaskeller/CoreLang.lhs
--- a/MagicHaskeller/CoreLang.lhs
+++ b/MagicHaskeller/CoreLang.lhs
@@ -91,6 +91,7 @@
 isa bits (Lambda e) = isa (bits `unsafeShiftL` 1) e `unsafeShiftR` 1
 isa bits (f :$ e )  = isa (isa bits f) e
 isa bits Primitive{} = bits
+isa bits PrimCon{}   = bits
 isa bits Context{}   = bits
 {- unused due to inefficiency
 ceToInteger (Lambda e)    = ceToInteger e -- 型が変わっちゃうのでLambdaは無視できるはず．...  といいつつ自信無．July 24, 2008のnotesを参照. ま，hashには使えるという程度のつもり．