diff --git a/.github/workflows/mutation-report.yml b/.github/workflows/mutation-report.yml
index 9a3d639..ba19107 100644
--- a/.github/workflows/mutation-report.yml
+++ b/.github/workflows/mutation-report.yml
@@ -63,7 +63,9 @@ jobs:
           bin=$(go env GOBIN)
           # gremlins reads the module root as `.`; given `./...` it finds no mutants at all. Each
           # mutant reruns the tests, and the default timeout times out a race-enabled suite.
-          "${bin:-$(go env GOPATH)/bin}/gremlins" unleash --diff "$BASE" --timeout-coefficient 40 \
+          # --integration runs every test per mutant: otherwise gremlins tests the directory named
+          # after the Go package, so a mutant in `package main` runs no tests and reads as survived.
+          "${bin:-$(go env GOPATH)/bin}/gremlins" unleash --integration --diff "$BASE" --timeout-coefficient 40 \
             --output "$RUNNER_TEMP/gremlins.json" .
 
       - name: Mutate the changed TypeScript
diff --git a/tests/test_mutation_report.py b/tests/test_mutation_report.py
index 5f4a6e0..f703b5d 100644
--- a/tests/test_mutation_report.py
+++ b/tests/test_mutation_report.py
@@ -130,3 +130,12 @@ def test_a_report_that_is_not_json_is_named_but_does_not_fail(self) -> None:
 
 if __name__ == "__main__":
     unittest.main()
+
+
+class TheWorkflow(unittest.TestCase):
+    def test_gremlins_runs_every_test_against_each_mutant(self) -> None:
+        # gremlins otherwise picks the package to test by finding a directory named after the Go
+        # package, so a mutant in `package main` under cmd/app runs no tests and reads as survived.
+        workflow = (Path(__file__).resolve().parents[1] / ".github/workflows/mutation-report.yml").read_text()
+        unleash = next(line for line in workflow.splitlines() if "gremlins\" unleash" in line)
+        self.assertIn("--integration", unleash)