diff --git a/ghc/lib/std/PrelHugs.lhs b/ghc/lib/std/PrelHugs.lhs
index b5d889b0fa6995b508815c4b9351af9f9dd8ac73..90aef89e9d4499ec2cfdd602a3eed60612a184db 100644
--- a/ghc/lib/std/PrelHugs.lhs
+++ b/ghc/lib/std/PrelHugs.lhs
@@ -18,7 +18,8 @@ module PrelHugs (
    fromDouble,
    hugsprimMkIO,
    hugsprimCreateAdjThunk,
-   hugsprimUnpackString
+   hugsprimUnpackString,
+   hugsprimPmFail
 )
 where
 import PrelGHC
@@ -82,6 +83,10 @@ hugsprimPmLe x y         = x <= y
 hugsprimUnpackString :: Addr -> String
 hugsprimUnpackString a = unpackCString a
 
+-- ToDo: make the message more informative.
+hugsprimPmFail       :: a
+hugsprimPmFail        = error "Pattern Match Failure"
+
 
 -- used when Hugs invokes top level function
 {-