diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog for the [`clash-ghc`](http://hackage.haskell.org/package/clash-ghc) package
 
+## 0.6.19 *June 9th 2016*
+* Fixes bugs:
+  * `Eq` instance of `Vec` sometimes not synthesisable
+  * VHDL: Converting product types to std_logic_vector fails when the `clash-hdlsyn Vivado` flag is enabled
+
 ## 0.6.18 *June 7th 2016*
 * New features:
   * DEC transformation also lifts HO-primitives applied to "interesting" primitives (i.e. `zipWith (*)`)
diff --git a/clash-ghc.cabal b/clash-ghc.cabal
--- a/clash-ghc.cabal
+++ b/clash-ghc.cabal
@@ -1,5 +1,5 @@
 Name:                 clash-ghc
-Version:              0.6.18
+Version:              0.6.19
 Synopsis:             CAES Language for Synchronous Hardware
 Description:
   CλaSH (pronounced ‘clash’) is a functional hardware description language that
@@ -94,11 +94,11 @@
                       unbound-generics          >= 0.1      && < 0.4,
                       unordered-containers      >= 0.2.1.0  && < 0.3,
 
-                      clash-lib                 >= 0.6.16   && < 0.7,
+                      clash-lib                 >= 0.6.17   && < 0.7,
                       clash-systemverilog       >= 0.6.6    && < 0.7,
-                      clash-vhdl                >= 0.6.12   && < 0.7,
+                      clash-vhdl                >= 0.6.13   && < 0.7,
                       clash-verilog             >= 0.6.6    && < 0.7,
-                      clash-prelude             >= 0.10.8   && < 0.11,
+                      clash-prelude             >= 0.10.9   && < 0.11,
                       ghc-typelits-extra        >= 0.1      && < 0.2,
                       ghc-typelits-natnormalise >= 0.3      && < 0.5,
                       deepseq                   >= 1.3.0.2  && < 1.5,
diff --git a/src-ghc/CLaSH/GHC/Evaluator.hs b/src-ghc/CLaSH/GHC/Evaluator.hs
--- a/src-ghc/CLaSH/GHC/Evaluator.hs
+++ b/src-ghc/CLaSH/GHC/Evaluator.hs
@@ -9,6 +9,7 @@
 
 module CLaSH.GHC.Evaluator where
 
+import           Control.Monad.Trans.Except (runExcept)
 import qualified Data.Bifunctor      as Bifunctor
 import           Data.Bits           (shiftL,shiftR)
 import qualified Data.Either         as Either
@@ -21,12 +22,12 @@
 import           CLaSH.Core.DataCon  (DataCon (..))
 import           CLaSH.Core.Literal  (Literal (..))
 import           CLaSH.Core.Term     (Term (..))
-import           CLaSH.Core.Type     (Type (..), ConstTy (..), LitTy (..),
+import           CLaSH.Core.Type     (Type (..), ConstTy (..),
                                       TypeView (..), tyView, mkFunTy,
                                       mkTyConApp, splitFunForallTy)
 import           CLaSH.Core.TyCon    (TyCon, TyConName, tyConDataCons)
 import           CLaSH.Core.TysPrim  (typeNatKind)
-import           CLaSH.Core.Util     (collectArgs,mkApps,mkVec,termType)
+import           CLaSH.Core.Util     (collectArgs,mkApps,mkVec,termType,tyNatSize)
 import           CLaSH.Core.Var      (Var (..))
 
 reduceConstant :: HashMap.HashMap TyConName TyCon -> Bool -> Term -> Term
@@ -244,14 +245,16 @@
 
   "CLaSH.Sized.Vector.replicate"
     | isSubj
-    , (TyConApp vecTcNm [LitTy (NumTy len),argTy]) <- tyView (runFreshM (termType tcm e))
+    , (TyConApp vecTcNm [lenTy,argTy]) <- tyView (runFreshM (termType tcm e))
+    , Right len <- runExcept (tyNatSize tcm lenTy)
     -> let (Just vecTc) = HashMap.lookup vecTcNm tcm
            [nilCon,consCon] = tyConDataCons vecTc
        in  mkVec nilCon consCon argTy len (replicate len (last $ Either.lefts args))
 
   "CLaSH.Sized.Vector.maxIndex"
     | isSubj
-    , [LitTy (NumTy n), _] <- Either.rights args
+    , [nTy, _] <- Either.rights args
+    , Right n <- runExcept (tyNatSize tcm nTy)
     -> let ty' = runFreshM (termType tcm e)
            (TyConApp intTcNm _) = tyView ty'
            (Just intTc) = HashMap.lookup intTcNm tcm
@@ -260,7 +263,8 @@
 
   "CLaSH.Sized.Vector.length"
     | isSubj
-    , [LitTy (NumTy n), _] <- Either.rights args
+    , [nTy, _] <- Either.rights args
+    , Right n <-runExcept (tyNatSize tcm nTy)
     -> let ty' = runFreshM (termType tcm e)
            (TyConApp intTcNm _) = tyView ty'
            (Just intTc) = HashMap.lookup intTcNm tcm