diff --git a/tests/wb_lazy_check.py b/tests/wb_lazy_check.py
index b066d7ae..5017842b 100644
--- a/tests/wb_lazy_check.py
+++ b/tests/wb_lazy_check.py
@@ -1,16 +1,27 @@
 """Build and run tests/wb_lazy_check.c: runtime/wb_lazy_choice.h, whether the lazy write-back runs, by the player's
 setting, the platform and the GPU driver.
 
+Needs a C compiler only: no Vulkan headers, no GPU and no game files.
+
 Usage: wb_lazy_check.py
 """
 import os
+import shutil
 import subprocess
 import sys
 from pathlib import Path
 
 ROOT = Path(__file__).resolve().parents[1]
-sys.path.insert(0, str(ROOT / 'tests' / 'diff'))
-from common import MSYS_BIN, compiler  # noqa: E402
+MSYS_BIN = Path(r'C:\msys64\ucrt64\bin')
+
+
+def compiler():
+    """$CC, else MSYS2 UCRT64's clang, else clang on PATH (as tests/diff/common.py picks it, without its Unicorn)."""
+    if os.environ.get('CC'):
+        return os.environ['CC']
+    if os.name == 'nt' and (MSYS_BIN / 'clang.exe').exists():
+        return str(MSYS_BIN / 'clang.exe')
+    return shutil.which('clang') or 'clang'
 
 
 def main():
@@ -22,7 +33,7 @@ def main():
         env['PATH'] = str(MSYS_BIN) + os.pathsep + env.get('PATH', '')
     # every platform's and driver's choice is checked through wb_lazy_choice's arguments; WBL_ON_WINDOWS on the one
     # built for
-    subprocess.check_call([compiler(), '-O1', '-Wall', '-Werror', '-I', str(ROOT / 'runtime'),
+    subprocess.check_call([compiler(), '-std=gnu11', '-O1', '-Wall', '-Werror', '-I', str(ROOT / 'runtime'),
                            str(ROOT / 'tests' / 'wb_lazy_check.c'), '-o', str(exe)], env=env)
     return subprocess.run([str(exe)], env=env).returncode