diff --git a/setup.py b/setup.py
index 9ec98f1..5dbceff 100644
--- a/setup.py
+++ b/setup.py
@@ -42,6 +42,7 @@
     install_requires=(
         "google-api-core >= 1.22.2, < 2.0.0dev",
         "proto-plus >= 1.4.0",
+        "packaging >= 14.3",
         "grpc-google-iam-v1 >= 0.12.3, < 0.13.0dev",
     ),
     python_requires=">=3.6",
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index 237151f..d9cdb59 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -8,3 +8,4 @@
 google-api-core==1.22.2
 proto-plus==1.4.0
 grpc-google-iam-v1==0.12.3
+packaging==14.3