diff --git a/clash-prelude/src/Clash/Prelude/BlockRam.hs b/clash-prelude/src/Clash/Prelude/BlockRam.hs
index 7c659fa8ff..748bff7647 100644
--- a/clash-prelude/src/Clash/Prelude/BlockRam.hs
+++ b/clash-prelude/src/Clash/Prelude/BlockRam.hs
@@ -838,11 +838,28 @@ blockRamPow2 = \cnt rd wrM -> withFrozenCallStack
 
 {- | Create a read-after-write block RAM from a read-before-write one
 
-#if __GLASGOW_HASKELL__ >= 908 && !defined(CLASH_MULTIPLE_HIDDEN)
+#if defined(CLASH_MULTIPLE_HIDDEN)
 >>> :t readNew (blockRam (0 :> 1 :> Nil))
 readNew (blockRam (0 :> 1 :> Nil))
   :: ...
      ...
+     ...
+     ... =>
+     Signal dom addr -> Signal dom (Maybe (addr, a)) -> Signal dom a
+
+#else
+#if __GLASGOW_HASKELL__ >= 908
+>>> :t readNew (blockRam (0 :> 1 :> Nil))
+readNew (blockRam (0 :> 1 :> Nil))
+  :: ...
+     ...
+     ... =>
+     Signal dom addr -> Signal dom (Maybe (addr, a)) -> Signal dom a
+
+#elif __GLASGOW_HASKELL__ >= 902
+>>> :t readNew (blockRam (0 :> 1 :> Nil))
+readNew (blockRam (0 :> 1 :> Nil))
+  :: ...
      ... =>
      Signal dom addr -> Signal dom (Maybe (addr, a)) -> Signal dom a
 
@@ -856,6 +873,7 @@ readNew (blockRam (0 :> 1 :> Nil))
      ... =>
      Signal dom addr -> Signal dom (Maybe (addr, a)) -> Signal dom a
 
+#endif
 #endif
 -}
 readNew
diff --git a/nix/overlay.nix b/nix/overlay.nix
index 40274a9f60..6324f0063f 100644
--- a/nix/overlay.nix
+++ b/nix/overlay.nix
@@ -48,6 +48,10 @@ let
           "ghc-typelits-natnormalise"
           "${ghc-typelits-natnormalise}"
           { };
+
+      # doctest-parallel = hprev.callHackage "doctest-parallel" "0.3.1" { };
+      doctest-parallel = hprev.callHackageDirect { pkg = "doctest-parallel"; ver = "0.3.1"; sha256 = "sha256-j0mk4RTEau6Cl90E8vMWZiA/ldRRurtLSYbGGE+q/vk="; } {};
+
     };
 
   # An overlay with the packages in this repository.