diff --git a/ghc/compiler/prelude/PrimOp.lhs b/ghc/compiler/prelude/PrimOp.lhs
index 9d7075acc1ebe955d5dc045768cde493762f27e6..3b35044daa6dd5f646b5cd1059e0a0e963ae3d11 100644
--- a/ghc/compiler/prelude/PrimOp.lhs
+++ b/ghc/compiler/prelude/PrimOp.lhs
@@ -856,6 +856,9 @@ primOpStrictness :: PrimOp -> ([Demand], Bool)
 	-- Use only the ones you ned.
 
 primOpStrictness SeqOp            = ([wwLazy], False)
+primOpStrictness ParOp            = ([wwLazy], False)
+primOpStrictness ForkOp		  = ([wwLazy, wwPrim], False)
+
 primOpStrictness NewArrayOp       = ([wwPrim, wwLazy, wwPrim], False)
 primOpStrictness WriteArrayOp     = ([wwPrim, wwPrim, wwLazy, wwPrim], False)