diff --git a/tests/test_sanity.py b/tests/test_sanity.py
index 58a8004f11106..0db37f1d10004 100644
--- a/tests/test_sanity.py
+++ b/tests/test_sanity.py
@@ -106,6 +106,9 @@ class sanity(RunnerCore):
   @classmethod
   def setUpClass(cls):
     super(sanity, cls).setUpClass()
+    # Unlike the other test suites we explicitly don't want to be skipping
+    # the sanity checks here
+    del os.environ['EMCC_SKIP_SANITY_CHECK']
     shutil.copyfile(CONFIG_FILE, CONFIG_FILE + '_backup')
 
     print()
diff --git a/tools/shared.py b/tools/shared.py
index 98c5525564098..17262316068d0 100644
--- a/tools/shared.py
+++ b/tools/shared.py
@@ -543,11 +543,14 @@ def check_sanity(force=False):
   EM_CONFIG (so, we re-check sanity when the settings are changed).  We also
   re-check sanity and clear the cache when the version changes.
   """
+  if not force and os.environ.get('EMCC_SKIP_SANITY_CHECK') == '1':
+    return
+  # We set EMCC_SKIP_SANITY_CHECK so that any subprocesses that we launch will
+  # not re-run the tests.
+  os.environ['EMCC_SKIP_SANITY_CHECK'] = '1'
   with ToolchainProfiler.profile_block('sanity'):
     check_llvm_version()
     expected = generate_sanity()
-    if os.environ.get('EMCC_SKIP_SANITY_CHECK') == '1':
-      return
     reason = None
     if not CONFIG_FILE:
       return # config stored directly in EM_CONFIG => skip sanity checks