diff --git a/flake.nix b/flake.nix
index f9e7fce..fda7173 100644
--- a/flake.nix
+++ b/flake.nix
@@ -112,6 +112,8 @@
                                            # Splits the monolithic Generated.Types (119 imports, ~287 MB
                                            # interface-file overflow in GHC 9.10.3) into two halves.
                                            # All awk/printf: no external file deps, no git-tracking required.
+                                           # -O0 keeps .hi files small (strips unfoldings/specialisations).
+                                           configureFlags = (old.configureFlags or "") + " --ghc-option=-O0";
                                            postUnpack = (old.postUnpack or "") + ''
                                                _types="$sourceRoot/build/Generated/Types.hs"