diff --git a/setup.py b/setup.py
index c36eb43..8a1a6c6 100644
--- a/setup.py
+++ b/setup.py
@@ -28,9 +28,9 @@
     # NOTE: Maintainers, please do not require google-api-core>=2.x.x
     # Until this issue is closed
     # https://github.com/googleapis/google-cloud-python/issues/10566
-    "google-api-core[grpc] >= 1.28.0, <3.0.0dev",
+    "google-api-core[grpc] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
     "grpc-google-iam-v1 >= 0.12.3, < 0.13dev",
-    "proto-plus >= 1.4.0",
+    "proto-plus >= 1.15.0",
 ]
 extras = {"libcst": "libcst >= 0.2.5"}
 
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index 0b8d52d..3755c96 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -5,7 +5,7 @@
 #
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have foo==1.14.0
-google-api-core==1.28.0
+google-api-core==1.31.5
 grpc-google-iam-v1==0.12.3
-proto-plus==1.4.0
+proto-plus==1.15.0
 libcst==0.2.5