diff --git a/flake.nix b/flake.nix
index 4917809..f9e7fce 100644
--- a/flake.nix
+++ b/flake.nix
@@ -152,11 +152,18 @@
                                                    'import Generated.TypesPart2' \
                                                    > "$_types"
 
-                                               # Add TypesPart1/TypesPart2 to cabal exposed-modules if absent.
-                                               # Write to same dir (not /tmp which is size-limited in sandbox).
+                                               # Add TypesPart1/TypesPart2 to cabal exposed-modules and add
+                                               # ghc-options: -O0 to keep interface file sizes below the
+                                               # GHC 9.10.3 binary-deserialisation limit (~287 MB).
+                                               # -O0 strips unfoldings/specialisations from .hi files,
+                                               # reducing them by ~10x so TypesPart*.hi stays well under the limit.
                                                _cabal=$(ls "$sourceRoot"/*.cabal | head -1)
                                                if ! grep -q 'Generated\.TypesPart1' "$_cabal"; then
-                                                   awk '/Generated\.LearningInsightInclude/{
+                                                   awk '/^    exposed-modules:/{
+                                                       print "    ghc-options: -O0"
+                                                       print
+                                                       next
+                                                   } /Generated\.LearningInsightInclude/{
                                                        print
                                                        print "        Generated.TypesPart1"
                                                        print "        Generated.TypesPart2"