diff --git a/csharp/generate_protos.sh b/csharp/generate_protos.sh
index 17b1640cb9..d747bff501 100755
--- a/csharp/generate_protos.sh
+++ b/csharp/generate_protos.sh
@@ -73,7 +73,8 @@ $PROTOC -Isrc -I. \
     src/google/protobuf/unittest_well_known_types.proto \
     src/google/protobuf/test_messages_proto3.proto \
     src/google/protobuf/test_messages_proto2.proto \
-    src/google/protobuf/unittest_proto3_optional.proto
+    src/google/protobuf/unittest_proto3_optional.proto \
+    src/google/protobuf/unittest_retention.proto
 
 # AddressBook sample protos
 $PROTOC -Iexamples -Isrc --csharp_out=csharp/src/AddressBook \