diff --git a/setup.py b/setup.py
index d73c3d4d..19afb1ca 100644
--- a/setup.py
+++ b/setup.py
@@ -32,6 +32,7 @@
     "google-api-core[grpc] >= 1.21.2, < 2.0.0dev",
     "grpc-google-iam-v1 >= 0.12.3, < 0.13dev",
     "proto-plus >= 1.4.0",
+    "packaging >= 14.3",
     "libcst >= 0.2.5",
 ]
 extras = {}
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index 399fa9e8..32665453 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -8,4 +8,5 @@
 google-api-core==1.26.3
 grpc-google-iam-v1==0.12.3
 proto-plus==1.4.0
-libcst==0.2.5
\ No newline at end of file
+libcst==0.2.5
+packaging==14.3