diff --git a/overlays/bootstrap.nix b/overlays/bootstrap.nix
index 0125b188f6..896270d4a9 100644
--- a/overlays/bootstrap.nix
+++ b/overlays/bootstrap.nix
@@ -82,6 +82,7 @@ in {
                 # will be applied to most versions of the GHC anyway (reordering the patches
                 # results in rebuilds of GHC and reduces sharing in /nix/store).
                 in until             "9.11"  ./patches/ghc/dll-loader-8.4.2.patch                                # https://gitlab.haskell.org/ghc/ghc/merge_requests/949  -- open
+                ++ fromUntil "9.4"   "9.12"  ./patches/ghc/ghc-9.4-9.6-9.8-disable-coreprep-spec-eval.patch      # causes more allocations
                 ++ until             "9.2"   ./patches/ghc/ghc-8.4.3-Cabal2201-no-hackage-tests.patch            # ?
                 ++ until             "9.2"   ./patches/ghc/cabal-host.patch                                      # https://github.com/haskell/cabal/issues/5887
                 ++ fromUntil "9.2"   "9.4"   ./patches/ghc/ghc-9.2-cabal-host.patch                              # https://github.com/haskell/cabal/issues/5887
diff --git a/overlays/patches/ghc/ghc-9.4-9.6-9.8-disable-coreprep-spec-eval.patch b/overlays/patches/ghc/ghc-9.4-9.6-9.8-disable-coreprep-spec-eval.patch
new file mode 100644
index 0000000000..75abfd400d
--- /dev/null
+++ b/overlays/patches/ghc/ghc-9.4-9.6-9.8-disable-coreprep-spec-eval.patch
@@ -0,0 +1,20 @@
+diff --git a/compiler/GHC/CoreToStg/Prep.hs b/compiler/GHC/CoreToStg/Prep.hs
+index c463f41121..3673b94991 100644
+--- a/compiler/GHC/CoreToStg/Prep.hs
++++ b/compiler/GHC/CoreToStg/Prep.hs
+@@ -1785,7 +1785,14 @@ mkFloat env dmd is_unlifted bndr rhs
+   where
+     is_hnf      = exprIsHNF rhs
+     is_strict   = isStrUsedDmd dmd
+-    ok_for_spec = exprOkForSpecEval (not . is_rec_call) rhs
++    ok_for_spec = exprOkForSpecEval fun_ok_for_spec rhs
++    fun_ok_for_spec i
++      | is_rec_call i = False
++      | otherwise     =
++          case idDetails i of
++                  DFunId {}        -> False
++                  DataConWorkId {} -> False
++                  _                -> True
+     is_rec_call = (`elemUnVarSet` cpe_rec_ids env)
+ 
+ emptyFloats :: Floats