diff --git a/noxfile.py b/noxfile.py
index 5bf628b..71ef308 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -123,6 +123,9 @@ def system(session):
     # Sanity check: Only run tests if the environment variable is set.
     if not os.environ.get("GOOGLE_APPLICATION_CREDENTIALS", ""):
         session.skip("Credentials must be set via environment variable")
+    # Install pyopenssl for mTLS testing.
+    if os.environ.get("GOOGLE_API_USE_CLIENT_CERTIFICATE", "false") == "true":
+        session.install("pyopenssl")
 
     system_test_exists = os.path.exists(system_test_path)
     system_test_folder_exists = os.path.exists(system_test_folder_path)
diff --git a/synth.metadata b/synth.metadata
index 804967a..827e050 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/python-secret-manager.git",
-        "sha": "4f3aab65f65fca38f826f6aa8d83c2860eaebcea"
+        "sha": "964c79e4c7006b7bfb64019635aa643964b65bab"
       }
     },
     {
@@ -19,14 +19,14 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "d17674372e27fb8f23013935e794aa37502071aa"
+        "sha": "0780323da96d5a53925fe0547757181fe76e8f1e"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "d17674372e27fb8f23013935e794aa37502071aa"
+        "sha": "0780323da96d5a53925fe0547757181fe76e8f1e"
       }
     }
   ],