diff --git a/src/compiler/api/GF/Compile/GeneratePMCFG.hs b/src/compiler/api/GF/Compile/GeneratePMCFG.hs
index 7ce0377f6..8bfe3ff6d 100644
--- a/src/compiler/api/GF/Compile/GeneratePMCFG.hs
+++ b/src/compiler/api/GF/Compile/GeneratePMCFG.hs
@@ -22,6 +22,7 @@ import Control.Monad (foldM,zipWithM,liftM,liftM2,forM,MonadPlus(..))
 import Control.Monad.Fix
 import Data.Maybe
 import Data.List(mapAccumL,sortBy,intersperse)
+import Data.Containers.ListUtils(nubOrd)
 import Prelude hiding ((<>))
 
 
@@ -73,7 +74,7 @@ pmcfgForm g t ctxt ty = do
   let (ms,s',t',arg_params) = apply 0 Map.empty unit ctxt t []
   let v = eval g [] s' t' []
   (ms,_,_,fn) <- breakDown g ms unit 0 [] v ty (return []) empty
-  runGenM g ms [] $ do
+  fmap nubOrd $ runGenM g ms [] $ do
     (r,rs,v,res_params) <- fn
     arg_params <- mapM params2int arg_params
     res_params <- params2int res_params
diff --git a/src/runtime/haskell/PGF2/Transactions.hsc b/src/runtime/haskell/PGF2/Transactions.hsc
index d3a197a3b..67f9e03d4 100644
--- a/src/runtime/haskell/PGF2/Transactions.hsc
+++ b/src/runtime/haskell/PGF2/Transactions.hsc
@@ -231,7 +231,6 @@ setConcreteFlag name value = Transaction $ \c_db _ c_revision c_exn ->
 
 type Token  = String
 
-type SeqId  = Int
 type LIndex = Int
 type LVar   = Int
 data LParam  = LParam {-# UNPACK #-} !LIndex [(LIndex,LVar)]
@@ -253,14 +252,11 @@ data Symbol
 
 type Quantifiers = [(LVar,Int)]
 data Rule = Rule Quantifiers LParam [LParam] LParam [Symbol]
-                 deriving (Eq,Show)
+                 deriving (Eq,Ord,Show)
 
 data PArg = PArg [(LIndex,LIndex)] {-# UNPACK #-} !LParam
             deriving (Eq,Show)
 
-data Production = Production [(LVar,LIndex)] [PArg] LParam [SeqId]
-                 deriving (Eq,Show)
-
 createLincat :: Cat -> [String] -> [Rule] -> [Rule] -> Transaction Concr ()
 createLincat name fields lindefs linrefs = Transaction $ \c_db c_abstr c_revision c_exn ->
   let n_fields = length fields