diff --git a/docker/03-custom-install.sh b/docker/03-custom-install.sh
index 8332180b..2fd2f560 100755
--- a/docker/03-custom-install.sh
+++ b/docker/03-custom-install.sh
@@ -28,8 +28,8 @@ pushd /tmp \
 
 # protoc, for proto-lens-combinators test suite
 # Instructions from: https://google.github.io/proto-lens/installing-protoc.html
-PROTOC_ZIP=protoc-3.3.0-linux-x86_64.zip
-curl -OL https://github.com/google/protobuf/releases/download/v3.3.0/$PROTOC_ZIP
+PROTOC_ZIP=protoc-28.0-linux-x86_64.zip
+curl -OL https://github.com/google/protobuf/releases/download/v28.0/$PROTOC_ZIP
 sudo unzip -o $PROTOC_ZIP -d /usr bin/protoc
 rm -f $PROTOC_ZIP