diff --git a/requirements.dev.txt b/requirements.dev.txt
index 10a66b3..8d3a527 100644
--- a/requirements.dev.txt
+++ b/requirements.dev.txt
@@ -11,6 +11,12 @@
 
 mysqlclient==1.4.6 --hash=sha256:f3fdaa9a38752a3b214a6fe79d7cae3653731a53e577821f9187e67cbecb2e16
 
+# Required by dev_appserver.py
+enum34==1.1.6 --hash=sha256:6bd0f6ad48ec2aa117d3d141940d484deccda84d4fcd884f5c3d93c23ecd8c79
+
+# Required by gae.py and by dev_appserver.py
+six==1.15.0 --hash=sha256:8b74bedcbbbaca38ff6d7491d76f2b06b3592611af620f8426e82dddb04a5ced
+
 # Required by grpc-google-iam-v1 <-- google-cloud-tasks
 # first sha is for cp27m-macosx_10_9_x86
 # second sha is for cp27mu-manylinux2010_x86
@@ -21,5 +27,7 @@
                --hash=sha256:5043440c45c0a031f387e7f48527541c65d672005fb24cf18ef6857483557d39
 
 # Required by google-cloud-tasks
-protobuf==3.12.4 --hash=sha256:3d59825cba9447e8f4fcacc1f3c892cafd28b964e152629b3f420a2fb5918b5a \
-                 --hash=sha256:6009f3ebe761fad319b52199a49f1efa7a3729302947a78a3f5ea8e7e89e3ac2
+# first sha is for cp27m-macosx_10_9_x86_64
+# second sha is for cp27mu-manylinux_2_5_x86_64.manylinux1_x86_64
+protobuf==3.17.3 --hash=sha256:ab6bb0e270c6c58e7ff4345b3a803cc59dbee19ddf77a4719c5b635f1d547aa8 \
+                 --hash=sha256:13ee7be3c2d9a5d2b42a1030976f760f28755fcf5863c55b1460fd205e6cd637