diff --git a/oi/ContainerInfo.cpp b/oi/ContainerInfo.cpp
index be6ee70..7d3d9ff 100644
--- a/oi/ContainerInfo.cpp
+++ b/oi/ContainerInfo.cpp
@@ -269,6 +269,10 @@ ContainerInfo::ContainerInfo(const fs::path& path) {
           codegenToml["traversal_func"].value<std::string>()) {
     codegen.traversalFunc = std::move(*str);
   }
+  if (std::optional<std::string> str =
+          codegenToml["extra"].value<std::string>()) {
+    codegen.extra = std::move(*str);
+  }
 
   if (toml::array* arr = codegenToml["processor"].as_array()) {
     codegen.processors.reserve(arr->size());
diff --git a/oi/ContainerInfo.h b/oi/ContainerInfo.h
index 7e15af3..776ab57 100644
--- a/oi/ContainerInfo.h
+++ b/oi/ContainerInfo.h
@@ -37,6 +37,7 @@ struct ContainerInfo {
     std::string func;
     std::string handler = "";
     std::string traversalFunc = "";
+    std::string extra = "";
     std::vector<Processor> processors{};
   };
 
diff --git a/types/README.md b/types/README.md
index 340fc10..1b70b4b 100644
--- a/types/README.md
+++ b/types/README.md
@@ -48,6 +48,12 @@ This document describes the format of the container definition files contained i
   `static types::st::Unit<DB> getSizeType(const T& container, ST returnArg)`
   where `ST` defines the combined static type of each supplied processor.
 
+- `extra`
+
+  Any extra C++ code to be included directly. This code is not automatically
+  wrapped in a namespace, so definitions from different container TOML files
+  will collide if they share the same name.
+
 
 ## Changes introduced with Typed Data Segment
 - `decl` and `func` fields are ignored when using `-ftyped-data-segment` and the