diff --git a/tools/check_test_registration.py b/tools/check_test_registration.py
index 0fb47521a..7b00d94d3 100644
--- a/tools/check_test_registration.py
+++ b/tools/check_test_registration.py
@@ -11,7 +11,17 @@ KNOWN_UNRUN = set()
 
 
 def built(build):
-    listed = subprocess.run(["ninja", "-C", str(build), "-t", "targets", "all"],
+    program, generator = None, None
+    for line in (Path(build) / "CMakeCache.txt").read_text(encoding="utf-8").splitlines():
+        if line.startswith("CMAKE_MAKE_PROGRAM:"):
+            program = line.partition("=")[2]
+        elif line.startswith("CMAKE_GENERATOR:"):
+            generator = line.partition("=")[2]
+    if generator not in ("Ninja", "Ninja Multi-Config"):
+        raise ValueError(f"test registration audit requires a Ninja generator, got {generator!r}")
+    if not program or program.endswith("-NOTFOUND"):
+        raise FileNotFoundError(f"CMAKE_MAKE_PROGRAM is not set in {Path(build) / 'CMakeCache.txt'}")
+    listed = subprocess.run([program, "-C", str(build), "-t", "targets", "all"],
                             capture_output=True, text=True, check=True).stdout
     names = set()
     for line in listed.splitlines():
diff --git a/tools/tests/test_test_registration.py b/tools/tests/test_test_registration.py
index 3d91bf0d6..e9862c2bc 100644
--- a/tools/tests/test_test_registration.py
+++ b/tools/tests/test_test_registration.py
@@ -1,4 +1,6 @@
 from pathlib import Path
+import os
+import shutil
 import sys
 import tempfile
 import unittest
@@ -36,13 +38,21 @@ class RegistrationTests(unittest.TestCase):
 
     def test_hyphenated_executable_is_discovered(self):
         output = "tests/buffer-bounds_tests: CXX_EXECUTABLE_LINKER\n"
-        with patch.object(check_test_registration.subprocess, "run", return_value=SimpleNamespace(stdout=output)):
-            self.assertEqual(check_test_registration.built("build"), {"buffer-bounds_tests"})
+        with tempfile.TemporaryDirectory() as directory:
+            build = Path(directory)
+            (build / "CMakeCache.txt").write_text("CMAKE_MAKE_PROGRAM:FILEPATH=/configured/ninja\nCMAKE_GENERATOR:INTERNAL=Ninja\n", encoding="utf-8")
+            with patch.object(check_test_registration.subprocess, "run", return_value=SimpleNamespace(stdout=output)) as run:
+                self.assertEqual(check_test_registration.built(build), {"buffer-bounds_tests"})
+            self.assertEqual(run.call_args[0][0][0], "/configured/ninja")
 
     def test_nested_test_output_is_discovered(self):
         output = "tests/gpu/buffer_bounds_tests: CXX_EXECUTABLE_LINKER\n"
-        with patch.object(check_test_registration.subprocess, "run", return_value=SimpleNamespace(stdout=output)):
-            self.assertEqual(check_test_registration.built("build"), {"buffer_bounds_tests"})
+        with tempfile.TemporaryDirectory() as directory:
+            build = Path(directory)
+            (build / "CMakeCache.txt").write_text("CMAKE_MAKE_PROGRAM:FILEPATH=/configured/ninja\nCMAKE_GENERATOR:INTERNAL=Ninja Multi-Config\n", encoding="utf-8")
+            with patch.object(check_test_registration.subprocess, "run", return_value=SimpleNamespace(stdout=output)) as run:
+                self.assertEqual(check_test_registration.built(build), {"buffer_bounds_tests"})
+            self.assertEqual(run.call_args[0][0][0], "/configured/ninja")
 
     def test_quoted_cmake_path_is_unescaped(self):
         names = self.registered(r'add_test("bounds" "/build/tests/a\"b_tests")' + '\n')
@@ -118,7 +128,28 @@ class RegistrationTests(unittest.TestCase):
             (external / "CTestTestfile.cmake").write_text(
                 'add_test("bounds" "/build/tests/buffer_bounds_tests")\n', encoding="utf-8")
             self.assertEqual(check_test_registration.registered(build), {"buffer_bounds_tests"})
+    def test_unsupported_generator_never_runs_build_tool(self):
+        for generator in ("Unix Makefiles", "Visual Studio 17 2022", ""):
+            with self.subTest(generator=generator), tempfile.TemporaryDirectory() as directory:
+                build = Path(directory)
+                (build / "CMakeCache.txt").write_text("CMAKE_MAKE_PROGRAM:FILEPATH=make\nCMAKE_GENERATOR:INTERNAL=" + generator + "\n", encoding="utf-8")
+                with patch.object(check_test_registration.subprocess, "run") as run:
+                    with self.assertRaisesRegex(ValueError, "requires a Ninja generator"):
+                        check_test_registration.built(build)
+                    run.assert_not_called()
 
+    def test_missing_make_program_never_runs_build_tool(self):
+        for program in (None, "", "CMAKE_MAKE_PROGRAM-NOTFOUND"):
+            with self.subTest(program=program), tempfile.TemporaryDirectory() as directory:
+                build = Path(directory)
+                cache = "CMAKE_GENERATOR:INTERNAL=Ninja\n"
+                if program is not None:
+                    cache += "CMAKE_MAKE_PROGRAM:FILEPATH=" + program + "\n"
+                (build / "CMakeCache.txt").write_text(cache, encoding="utf-8")
+                with patch.object(check_test_registration.subprocess, "run") as run:
+                    with self.assertRaises(FileNotFoundError):
+                        check_test_registration.built(build)
+                    run.assert_not_called()
 
 if __name__ == "__main__":
     unittest.main()