diff --git a/README.md b/README.md
index 2a03c0d..1a694ef 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,8 @@
 # Protoc Docker
 
 Docker container for generating protobuf code. Right now used in CI only for other projects.
+Smallish image size (~220mb); unfortunately the grpc-swift plugins cause it to blow out as they're statically linked (so don't need foundation or the swift dependencies).
+Not copying them across will save ~100mb in space.
 
 ## TODOS