diff --git a/synthtool/gcp/common.py b/synthtool/gcp/common.py
index c21fbc493..9181e375e 100644
--- a/synthtool/gcp/common.py
+++ b/synthtool/gcp/common.py
@@ -76,11 +76,20 @@ def py_library(self, **kwargs) -> Path:
 
         # Set default Python versions for noxfile.py
         if "default_python_version" not in kwargs:
-            kwargs["default_python_version"] = "3.7"
+            kwargs["default_python_version"] = "3.8"
         if "unit_test_python_versions" not in kwargs:
-            kwargs["unit_test_python_versions"] = ["2.7", "3.5", "3.6", "3.7", "3.8"]
+            kwargs["unit_test_python_versions"] = ["3.6", "3.7", "3.8"]
+            if "microgenerator" not in kwargs:
+                kwargs["unit_test_python_versions"] = ["2.7", "3.5"] + kwargs[
+                    "unit_test_python_versions"
+                ]
+
         if "system_test_python_versions" not in kwargs:
-            kwargs["system_test_python_versions"] = ["2.7", "3.7"]
+            kwargs["system_test_python_versions"] = ["3.8"]
+            if "microgenerator" not in kwargs:
+                kwargs["system_test_python_versions"] = ["2.7"] + kwargs[
+                    "system_test_python_versions"
+                ]
 
         # Don't add samples templates if there are no samples
         if "samples" not in kwargs:
diff --git a/synthtool/gcp/templates/python_library/noxfile.py.j2 b/synthtool/gcp/templates/python_library/noxfile.py.j2
index 46657f29b..852bc7547 100644
--- a/synthtool/gcp/templates/python_library/noxfile.py.j2
+++ b/synthtool/gcp/templates/python_library/noxfile.py.j2
@@ -72,6 +72,10 @@ def lint_setup_py(session):
 
 def default(session):
     # Install all test dependencies, then install this package in-place.
+
+    {%- if microgenerator %}
+    session.install("asyncmock", "pytest-asyncio")
+    {% endif -%}
     session.install("mock", "pytest", "pytest-cov")
     session.install("-e", "."){% for dependency in unit_test_dependencies %}
     session.install("-e", "{{dependency}}"){% endfor %}