GHC 6.5 error? Illegal polymorphic or qualified type

Hello, I tried to compile HAppS using the latest GHC snapshot (in compiles fine with 6.41). I for example get the error /home/rene/repos/HAppS/src/HAppS/MACID/Var.hs:23:0: Illegal polymorphic or qualified type: forall state event. Ev state event (ref t) In the type signature for `newEmptyRef': newEmptyRef :: (Monoid t, Ref ref) => AnyEv (ref t) Note that AnyEv is defined as type AnyEv a = forall state event. Ev state event a This should be OK shouldn't it? At least in works in 6.41 and everythis is quantified. Exactly what does the error message Illegal polymorphic or qualified type mean? Rene.