diff --git a/monitoring/snippets/v3/alerts-client/noxfile.py b/monitoring/snippets/v3/alerts-client/noxfile.py
index 5ff9e1db5808..6a8ccdae22c9 100644
--- a/monitoring/snippets/v3/alerts-client/noxfile.py
+++ b/monitoring/snippets/v3/alerts-client/noxfile.py
@@ -28,8 +28,9 @@
 # WARNING - WARNING - WARNING - WARNING - WARNING
 # WARNING - WARNING - WARNING - WARNING - WARNING
 
-# Copy `noxfile_config.py` to your directory and modify it instead.
+BLACK_VERSION = "black==19.10b0"
 
+# Copy `noxfile_config.py` to your directory and modify it instead.
 
 # `TEST_CONFIG` dict is a configuration hook that allows users to
 # modify the test configurations. The values here should be in sync
@@ -159,7 +160,7 @@ def lint(session: nox.sessions.Session) -> None:
 
 @nox.session
 def blacken(session: nox.sessions.Session) -> None:
-    session.install("black")
+    session.install(BLACK_VERSION)
     python_files = [path for path in os.listdir(".") if path.endswith(".py")]
 
     session.run("black", *python_files)
diff --git a/monitoring/snippets/v3/cloud-client/noxfile.py b/monitoring/snippets/v3/cloud-client/noxfile.py
index 5ff9e1db5808..6a8ccdae22c9 100644
--- a/monitoring/snippets/v3/cloud-client/noxfile.py
+++ b/monitoring/snippets/v3/cloud-client/noxfile.py
@@ -28,8 +28,9 @@
 # WARNING - WARNING - WARNING - WARNING - WARNING
 # WARNING - WARNING - WARNING - WARNING - WARNING
 
-# Copy `noxfile_config.py` to your directory and modify it instead.
+BLACK_VERSION = "black==19.10b0"
 
+# Copy `noxfile_config.py` to your directory and modify it instead.
 
 # `TEST_CONFIG` dict is a configuration hook that allows users to
 # modify the test configurations. The values here should be in sync
@@ -159,7 +160,7 @@ def lint(session: nox.sessions.Session) -> None:
 
 @nox.session
 def blacken(session: nox.sessions.Session) -> None:
-    session.install("black")
+    session.install(BLACK_VERSION)
     python_files = [path for path in os.listdir(".") if path.endswith(".py")]
 
     session.run("black", *python_files)
diff --git a/monitoring/snippets/v3/uptime-check-client/noxfile.py b/monitoring/snippets/v3/uptime-check-client/noxfile.py
index 5ff9e1db5808..6a8ccdae22c9 100644
--- a/monitoring/snippets/v3/uptime-check-client/noxfile.py
+++ b/monitoring/snippets/v3/uptime-check-client/noxfile.py
@@ -28,8 +28,9 @@
 # WARNING - WARNING - WARNING - WARNING - WARNING
 # WARNING - WARNING - WARNING - WARNING - WARNING
 
-# Copy `noxfile_config.py` to your directory and modify it instead.
+BLACK_VERSION = "black==19.10b0"
 
+# Copy `noxfile_config.py` to your directory and modify it instead.
 
 # `TEST_CONFIG` dict is a configuration hook that allows users to
 # modify the test configurations. The values here should be in sync
@@ -159,7 +160,7 @@ def lint(session: nox.sessions.Session) -> None:
 
 @nox.session
 def blacken(session: nox.sessions.Session) -> None:
-    session.install("black")
+    session.install(BLACK_VERSION)
     python_files = [path for path in os.listdir(".") if path.endswith(".py")]
 
     session.run("black", *python_files)