diff --git a/flake.nix b/flake.nix
index 5cb0636..fed26bb 100644
--- a/flake.nix
+++ b/flake.nix
@@ -160,7 +160,14 @@
         checks.package = sausage;
         checks.tests = craneLib.cargoTest (common // wasiCcEnv // {
           inherit cargoArtifacts;
-          cargoExtraArgs = "--workspace --lib --test harness --test p1 --test durable --test 'cred*' --test layers --test regressions --test streams --test wasi";
+          # Keep the same sandbox-compatible modules in the shared host test executable.
+          checkPhaseCargoCommand = ''
+            cargoWithProfile test --locked --workspace --lib
+            cargoWithProfile test --locked -p sausage --test it -- \
+              harness:: p1:: durable:: cred:: cred_ --skip undo_harness::
+            cargoWithProfile test --locked -p sausage-vfs \
+              --test layers --test regressions --test streams --test wasi
+          '';
           preCheck = ''
             export SAUSAGE_CACHE="$TMPDIR/sausage-cache"
             export CARGO_TARGET_DIR="$PWD/target"