diff --git a/crates/wasi/src/lib.rs b/crates/wasi/src/lib.rs
index ab52d3270c..ff04a257d6 100644
--- a/crates/wasi/src/lib.rs
+++ b/crates/wasi/src/lib.rs
@@ -8,6 +8,7 @@ pub use wasi_common::{WasiCtx, WasiCtxBuilder};
 // with all the various WASI exports.
 wasmtime_wiggle::define_struct_for_wiggle!({
     witx: ["../wasi-common/WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx"],
+    ctx: WasiCtx,
 });
 
 pub fn is_wasi_module(name: &str) -> bool {
diff --git a/crates/wiggle/wasmtime/macro/src/config.rs b/crates/wiggle/wasmtime/macro/src/config.rs
index 5834980293..82839dd360 100644
--- a/crates/wiggle/wasmtime/macro/src/config.rs
+++ b/crates/wiggle/wasmtime/macro/src/config.rs
@@ -6,22 +6,25 @@ use {
         punctuated::Punctuated,
         Error, Result, Token,
     },
-    wiggle_generate::config::WitxConf,
+    wiggle_generate::config::{CtxConf, WitxConf},
 };
 
 #[derive(Debug, Clone)]
 pub struct Config {
     pub witx: WitxConf,
+    pub ctx: CtxConf,
 }
 
 #[derive(Debug, Clone)]
 pub enum ConfigField {
     Witx(WitxConf),
+    Ctx(CtxConf),
 }
 
 mod kw {
     syn::custom_keyword!(witx);
     syn::custom_keyword!(witx_literal);
+    syn::custom_keyword!(ctx);
 }
 
 impl Parse for ConfigField {
@@ -35,6 +38,10 @@ impl Parse for ConfigField {
             input.parse::<kw::witx_literal>()?;
             input.parse::<Token![:]>()?;
             Ok(ConfigField::Witx(WitxConf::Literal(input.parse()?)))
+        } else if lookahead.peek(kw::ctx) {
+            input.parse::<kw::ctx>()?;
+            input.parse::<Token![:]>()?;
+            Ok(ConfigField::Ctx(input.parse()?))
         } else {
             Err(lookahead.error())
         }
@@ -44,6 +51,7 @@ impl Parse for ConfigField {
 impl Config {
     pub fn build(fields: impl Iterator<Item = ConfigField>, err_loc: Span) -> Result<Self> {
         let mut witx = None;
+        let mut ctx = None;
         for f in fields {
             match f {
                 ConfigField::Witx(c) => {
@@ -52,12 +60,21 @@ impl Config {
                     }
                     witx = Some(c);
                 }
+                ConfigField::Ctx(c) => {
+                    if ctx.is_some() {
+                        return Err(Error::new(err_loc, "duplicate `ctx` field"));
+                    }
+                    ctx = Some(c);
+                }
             }
         }
         Ok(Config {
             witx: witx
                 .take()
                 .ok_or_else(|| Error::new(err_loc, "`witx` field required"))?,
+            ctx: ctx
+                .take()
+                .ok_or_else(|| Error::new(err_loc, "`ctx` field required"))?,
         })
     }
 
diff --git a/crates/wiggle/wasmtime/macro/src/lib.rs b/crates/wiggle/wasmtime/macro/src/lib.rs
index e145853a6d..2ff7e08d06 100644
--- a/crates/wiggle/wasmtime/macro/src/lib.rs
+++ b/crates/wiggle/wasmtime/macro/src/lib.rs
@@ -2,9 +2,9 @@ use proc_macro::TokenStream;
 use proc_macro2::{Ident, Span, TokenStream as TokenStream2};
 use quote::{format_ident, quote};
 use syn::parse_macro_input;
+use wiggle_generate::Names;
 
 mod config;
-mod utils;
 
 #[proc_macro]
 pub fn define_struct_for_wiggle(args: TokenStream) -> TokenStream {
@@ -13,7 +13,9 @@ pub fn define_struct_for_wiggle(args: TokenStream) -> TokenStream {
         std::env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR env var"),
     );
     let doc = config.load_document();
-    generate(&doc).into()
+    let names = Names::new(&config.ctx.name, quote!(wasmtime_wiggle));
+
+    generate(&doc, &names).into()
 }
 
 enum Abi {
@@ -23,7 +25,7 @@ enum Abi {
     F64,
 }
 
-fn generate(doc: &witx::Document) -> TokenStream2 {
+fn generate(doc: &witx::Document, names: &Names) -> TokenStream2 {
     let mut fields = Vec::new();
     let mut get_exports = Vec::new();
     let mut ctor_externs = Vec::new();
@@ -59,7 +61,7 @@ fn generate(doc: &witx::Document) -> TokenStream2 {
             let mut hostcall_args = Vec::new();
 
             for param in func.params.iter() {
-                let name = utils::param_name(param);
+                let name = names.func_param(&param.name);
 
                 // Registers a new parameter to the shim we're making with the
                 // given `name`, the `abi_ty` wasm type and `hex` defines
diff --git a/crates/wiggle/wasmtime/macro/src/utils.rs b/crates/wiggle/wasmtime/macro/src/utils.rs
deleted file mode 100644
index d0bd3b334a..0000000000
--- a/crates/wiggle/wasmtime/macro/src/utils.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-use proc_macro2::Ident;
-
-pub fn param_name(param: &witx::InterfaceFuncParam) -> Ident {
-    quote::format_ident!(
-        "{}",
-        match param.name.as_str() {
-            "in" | "type" => format!("r#{}", param.name.as_str()),
-            s => s.to_string(),
-        }
-    )
-}