diff --git a/src/compiler/GF/Command/Commands.hs b/src/compiler/GF/Command/Commands.hs
index 2e989a712..d000b35b0 100644
--- a/src/compiler/GF/Command/Commands.hs
+++ b/src/compiler/GF/Command/Commands.hs
@@ -43,7 +43,7 @@ instance (Monad m,HasPGF m,Fail.MonadFail m) => TypeCheckArg m where
                                            (inferExpr pgf e)
                         Nothing  -> fail "Import a grammar before using this command"
 
-pgfCommands :: (HasPGF m, MonadFail m) => Map.Map String (CommandInfo m)
+pgfCommands :: (HasPGF m, Fail.MonadFail m) => Map.Map String (CommandInfo m)
 pgfCommands = Map.fromList [
   ("aw", emptyCommandInfo {
      longname = "align_words",
diff --git a/src/compiler/GF/Compile/Compute/Concrete.hs b/src/compiler/GF/Compile/Compute/Concrete.hs
index aede6b7aa..834e596e2 100644
--- a/src/compiler/GF/Compile/Compute/Concrete.hs
+++ b/src/compiler/GF/Compile/Compute/Concrete.hs
@@ -584,11 +584,19 @@ instance Functor ConstValue where
 instance Applicative ConstValue where
   pure = Const
 
+  (Const f) <*> (Const x) = Const (f x)
+  NonExist  <*> _         = NonExist
+  _         <*> NonExist  = NonExist
+  RunTime   <*>  _        = RunTime
+  _         <*>  RunTime  = RunTime
+
+#if MIN_VERSION_base(4,10,0)
   liftA2 f (Const a) (Const b) = Const (f a b)
   liftA2 f NonExist  _         = NonExist
   liftA2 f _         NonExist  = NonExist
   liftA2 f RunTime   _         = RunTime
   liftA2 f _         RunTime   = RunTime
+#endif
 
 value2string v = fmap (unwords.snd) (value2string v False [])
   where