diff --git a/nix/overlay-ghc902.nix b/nix/overlay-ghc902.nix
index 9c0f561e41..df9ead575d 100644
--- a/nix/overlay-ghc902.nix
+++ b/nix/overlay-ghc902.nix
@@ -10,16 +10,13 @@ in
 
   # Marked as broken in nixpkgs since it needs a newer hashable than the one
   # in the .cabal file uplodaed to hackage.
-  concurrent-supply = doJailbreak (markUnbroken prev.concurrent-supply);
+  # concurrent-supply = doJailbreak (markUnbroken prev.concurrent-supply);
 
   # Marked as broken in nixpkgs for this version of GHC.
   docopt = markUnbroken prev.docopt;
 
   # The doctests crash for this package, but the main testsuite passes.
-  generic-lens = dontCheck prev.generic-lens;
-
-  # For some reason, lens 5.1.1 didn't build properly.
-  lens = prev.lens_5_2_2;
+  # generic-lens = dontCheck prev.generic-lens;
 
   # Marked as broken in nixpkgs, since it specifies much older dependencies
   # than the defaults in nixpkgs.
diff --git a/nix/overlay-ghc962.nix b/nix/overlay-ghc962.nix
index 662fbbbd44..ac090eb8ed 100644
--- a/nix/overlay-ghc962.nix
+++ b/nix/overlay-ghc962.nix
@@ -46,4 +46,15 @@ in
 
   # Needs a newer base than the .cabal file currently uploaded to hackage.
   vector-binary-instances = doJailbreak prev.vector-binary-instances;
+
+  # Use a newer version than the default in nixpkgs.
+  th-abstraction = prev.th-abstraction_0_5_0_0;
+
+  # Use a newer version than the default in nixpkgs.
+  # doctest = prev.doctest_0_18_2;
+
+  # We can't use newer than 1.12 here: we need singletons 3.x (due to the cabal
+  # file of `clash-testsuite`) but the changed `DConP` constructor in 1.13
+  # stops `singletons-th` from building.
+  doctest = prev.callHackage "doctest" "0.21.1" { };
 }