diff --git a/flake.nix b/flake.nix
index faa4236..9ef1e1c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -124,6 +124,7 @@
                                            configureFlags = (old.configureFlags or []) ++ [
                                                "--ghc-option=-O0"
                                                "--ghc-option=-fomit-interface-pragmas"
+                                               "--ghc-option=-ddump-if-trace"
                                            ];
                                            postUnpack = (old.postUnpack or "") + ''
                                                _actual="$sourceRoot/build/Generated/ActualTypes.hs"