diff --git a/src/fsharp/Optimizer.fs b/src/fsharp/Optimizer.fs
index 25a1dfd2fe4..18f46a7e5ab 100644
--- a/src/fsharp/Optimizer.fs
+++ b/src/fsharp/Optimizer.fs
@@ -494,7 +494,7 @@ let BindTypeVarsToUnknown (tps:Typar list) env =
                 tp.Data.typar_id <- ident (nm,tp.Range));      
     List.fold (fun sofar arg -> BindTypeVar arg UnknownTypeValue sofar) env tps 
 
-let BindCcu (ccu:Tast.CcuThunk) mval env cenv = 
+let BindCcu (ccu:Tast.CcuThunk) mval env (cenv:cenv) = 
 #if DEBUG
     if verboseOptimizationInfo then 
         dprintf "*** Reloading optimization data for assembly %s, info = \n%s\n" ccu.AssemblyName (showL (Layout.squashTo 192 (moduleInfoL cenv mval)));