diff --git a/flake.nix b/flake.nix
index 5543231..cc634c3 100644
--- a/flake.nix
+++ b/flake.nix
@@ -126,6 +126,7 @@
                                                "--ghc-option=-fomit-interface-pragmas"
                                                "--disable-split-sections"
                                                "--ghc-option=-j1"
+                                               "--ghc-option=-fexternal-interpreter"
                                            ];
                                            postUnpack = (old.postUnpack or "") + ''
                                                _actual="$sourceRoot/build/Generated/ActualTypes.hs"