diff --git a/Cargo.lock b/Cargo.lock
index 6eac4e468..65179de8d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3425,8 +3425,8 @@ name = "test-helpers"
 version = "0.0.0"
 dependencies = [
  "codegen-macro",
- "wit-bindgen-core 0.37.0",
- "wit-parser 0.223.1",
+ "wit-bindgen-core 0.38.0",
+ "wit-parser 0.224.1",
 ]
 
 [[package]]
@@ -4381,9 +4381,9 @@ dependencies = [
 
 [[package]]
 name = "wasmparser"
-version = "0.223.1"
+version = "0.224.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "664b980991ed9a8c834eb528a8979ab1109edcf52dc05dd5751e2cc3fb31035d"
+checksum = "04f17a5917c2ddd3819e84c661fae0d6ba29d7b9c1f0e96c708c65a9c4188e11"
 dependencies = [
  "bitflags",
  "indexmap",
@@ -5168,13 +5168,13 @@ checksum = "1ebf944e87a7c253233ad6766e082e3cd714b5d03812acc24c318f549614536e"
 
 [[package]]
 name = "wit-bindgen-core"
-version = "0.37.0"
+version = "0.38.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8ba105733ba146c94e067793fb46505265ea8720eb14ceae65b10797c7728a65"
+checksum = "70e2f98d49960a416074c5d72889f810ed3032a32ffef5e4760094426fefbfe8"
 dependencies = [
  "anyhow",
  "heck",
- "wit-parser 0.223.1",
+ "wit-parser 0.224.1",
 ]
 
 [[package]]
@@ -5285,7 +5285,7 @@ dependencies = [
  "clap",
  "heck",
  "test-helpers",
- "wit-bindgen-core 0.37.0",
+ "wit-bindgen-core 0.38.0",
  "wrpc-introspect",
 ]
 
@@ -5304,7 +5304,7 @@ dependencies = [
  "syn",
  "test-helpers",
  "tokio",
- "wit-bindgen-core 0.37.0",
+ "wit-bindgen-core 0.38.0",
  "wit-bindgen-wrpc",
  "wrpc-introspect",
  "wrpc-transport",
@@ -5319,7 +5319,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "syn",
- "wit-bindgen-core 0.37.0",
+ "wit-bindgen-core 0.38.0",
  "wit-bindgen-wrpc-rust",
 ]
 
@@ -5382,9 +5382,9 @@ dependencies = [
 
 [[package]]
 name = "wit-parser"
-version = "0.223.1"
+version = "0.224.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "263fde17f1fbe55a413f16eb59094bf751795c6da469a05c3d45ea6c77df6b40"
+checksum = "e3477d8d0acb530d76beaa8becbdb1e3face08929db275f39934963eb4f716f8"
 dependencies = [
  "anyhow",
  "id-arena",
@@ -5395,7 +5395,7 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "unicode-xid",
- "wasmparser 0.223.1",
+ "wasmparser 0.224.1",
 ]
 
 [[package]]
@@ -5496,7 +5496,7 @@ dependencies = [
  "wasmtime",
  "wasmtime-cli-flags",
  "wasmtime-wasi",
- "wit-bindgen-core 0.37.0",
+ "wit-bindgen-core 0.38.0",
  "wit-bindgen-wrpc",
  "wit-bindgen-wrpc-go",
  "wit-bindgen-wrpc-rust",
@@ -5525,7 +5525,7 @@ dependencies = [
 name = "wrpc-introspect"
 version = "0.7.0"
 dependencies = [
- "wit-parser 0.223.1",
+ "wit-parser 0.224.1",
 ]
 
 [[package]]
@@ -5655,7 +5655,7 @@ dependencies = [
  "wasm-tokio",
  "wasmtime",
  "wasmtime-wasi",
- "wit-parser 0.223.1",
+ "wit-parser 0.224.1",
  "wrpc-introspect",
  "wrpc-transport",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 0e949b570..bc9f300b6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -179,13 +179,13 @@ wasmtime-cli-flags = { version = "45", default-features = false }
 wasmtime-wasi = { version = "45", default-features = false }
 wasmtime-wasi-http = { version = "45", default-features = false }
 wit-bindgen = { version = "0.45", default-features = false }
-wit-bindgen-core = { version = "0.37", default-features = false }
+wit-bindgen-core = { version = "0.38", default-features = false }
 wit-bindgen-wrpc = { version = "0.11", default-features = false, path = "./crates/wit-bindgen" }
 wit-bindgen-wrpc-go = { version = "0.13", default-features = false, path = "./crates/wit-bindgen-go" }
 wit-bindgen-wrpc-rust = { version = "0.11", default-features = false, path = "./crates/wit-bindgen-rust" }
 wit-bindgen-wrpc-rust-macro = { version = "0.11", default-features = false, path = "./crates/wit-bindgen-rust-macro" }
 wit-component = { version = "0.252", default-features = false }
-wit-parser = { version = "0.223", default-features = false }
+wit-parser = { version = "0.224", default-features = false }
 wrpc-cli = { version = "0.8", path = "./crates/cli", default-features = false }
 wrpc-introspect = { version = "0.7", default-features = false, path = "./crates/introspect" }
 wrpc-nats = { version = "0.1", path = "./crates/nats", default-features = false }
diff --git a/crates/introspect/src/lib.rs b/crates/introspect/src/lib.rs
index 5744ccf88..50a955152 100644
--- a/crates/introspect/src/lib.rs
+++ b/crates/introspect/src/lib.rs
@@ -190,13 +190,15 @@ pub fn async_paths_tyid(resolve: &Resolve, id: TypeId) -> (BTreeSet<VecDeque<Opt
         }
         TypeDefKind::Stream(element) => {
             let mut paths = BTreeSet::new();
-            let (nested, fut) = async_paths_ty(resolve, element);
-            for mut path in nested {
-                path.push_front(None);
-                paths.insert(path);
-            }
-            if fut {
-                paths.insert(vec![None].into());
+            if let Some(ty) = element {
+                let (nested, fut) = async_paths_ty(resolve, ty);
+                for mut path in nested {
+                    path.push_front(None);
+                    paths.insert(path);
+                }
+                if fut {
+                    paths.insert(vec![None].into());
+                }
             }
             (paths.into_iter().collect(), true)
         }
diff --git a/crates/wit-bindgen-go/src/interface.rs b/crates/wit-bindgen-go/src/interface.rs
index c17a0bf42..7ca6b7af5 100644
--- a/crates/wit-bindgen-go/src/interface.rs
+++ b/crates/wit-bindgen-go/src/interface.rs
@@ -1069,8 +1069,8 @@ impl InterfaceGenerator<'_> {
         }
     }
 
-    fn print_read_stream(&mut self, element: &Type, reader: &str, path: &str) {
-        match Some(element) {
+    fn print_read_stream(&mut self, element: &Option<Type>, reader: &str, path: &str) {
+        match element {
             Some(ty) if is_ty(self.resolve, Type::U8, ty) => {
                 let bytes = self.deps.bytes();
                 let io = self.deps.io();
@@ -2065,8 +2065,8 @@ impl InterfaceGenerator<'_> {
         }
     }
 
-    fn print_write_stream(&mut self, element: &Type, name: &str, writer: &str) {
-        match Some(element) {
+    fn print_write_stream(&mut self, element: &Option<Type>, name: &str, writer: &str) {
+        match element {
             Some(ty) if is_ty(self.resolve, Type::U8, ty) => {
                 let fmt = self.deps.fmt();
                 let io = self.deps.io();
@@ -3256,8 +3256,8 @@ func ServeInterface(s {wrpc}.Server, h Handler) (stop func() error, err error) {
         }
     }
 
-    fn print_stream(&mut self, element: &Type) {
-        match Some(element) {
+    fn print_stream(&mut self, element: &Option<Type>) {
+        match element {
             Some(ty) if is_ty(self.resolve, Type::U8, ty) => {
                 let io = self.deps.io();
                 self.push_str(io);
@@ -3884,7 +3884,7 @@ func (v *{name}) WriteToIndex(w {wrpc}.ByteWriter) (func({wrpc}.IndexWriter) err
         }
     }
 
-    fn type_stream(&mut self, id: TypeId, _name: &str, ty: &Type, docs: &Docs) {
+    fn type_stream(&mut self, id: TypeId, _name: &str, ty: &Option<Type>, docs: &Docs) {
         if let Some(name) = self.name_of(id) {
             self.godoc(docs);
             uwrite!(self.src, "type {name} = ");
diff --git a/crates/wit-bindgen-rust/src/interface.rs b/crates/wit-bindgen-rust/src/interface.rs
index 975bacbe0..7e4893e87 100644
--- a/crates/wit-bindgen-rust/src/interface.rs
+++ b/crates/wit-bindgen-rust/src/interface.rs
@@ -998,13 +998,17 @@ pub fn serve_interface<'a, T: {wrpc_transport}::Serve>(
         self.push_str("> + ::core::marker::Send>>");
     }
 
-    fn print_stream(&mut self, element: &Type, submodule: bool) {
+    fn print_stream(&mut self, element: &Option<Type>, submodule: bool) {
         uwrite!(
             self.src,
             "::core::pin::Pin<::std::boxed::Box<dyn {futures}::Stream<Item = ",
             futures = self.gen.futures_path()
         );
-        self.print_list(element, true, submodule);
+        if let Some(ty) = element {
+            self.print_list(ty, true, submodule);
+        } else {
+            self.push_str("Vec<()>");
+        }
         self.push_str("> + ::core::marker::Send>>");
     }
 
@@ -2468,7 +2472,7 @@ mod {mod_name} {{
         }
     }
 
-    fn type_stream(&mut self, id: TypeId, _name: &str, ty: &Type, docs: &Docs) {
+    fn type_stream(&mut self, id: TypeId, _name: &str, ty: &Option<Type>, docs: &Docs) {
         if let Some(name) = self.name_of(id) {
             self.rustdoc(docs);
             uwrite!(self.src, "pub type {name} = ");
diff --git a/tests/codegen/futures.wit b/tests/codegen/futures.wit
index 2d634a400..ff24a5098 100644
--- a/tests/codegen/futures.wit
+++ b/tests/codegen/futures.wit
@@ -13,7 +13,7 @@ interface futures {
   future-f32-param: func(x: future<f32>);
   future-f64-param: func(x: future<f64>);
 
-  future-ret: func(x: future);
+  future-ret: func() -> future;
   future-u8-ret: func() -> future<u8>;
   future-u16-ret: func() -> future<u16>;
   future-u32-ret: func() -> future<u32>;
diff --git a/tests/codegen/streams.wit b/tests/codegen/streams.wit
index 7ed696ed8..96ccfeed2 100644
--- a/tests/codegen/streams.wit
+++ b/tests/codegen/streams.wit
@@ -15,6 +15,7 @@ interface transmit {
 }
 
 interface streams {
+  stream-param: func(x: stream);
   stream-u8-param: func(x: stream<u8>);
   stream-u16-param: func(x: stream<u16>);
   stream-u32-param: func(x: stream<u32>);
@@ -26,6 +27,7 @@ interface streams {
   stream-f32-param: func(x: stream<f32>);
   stream-f64-param: func(x: stream<f64>);
 
+  stream-ret: func() -> stream;
   stream-u8-ret: func() -> stream<u8>;
   stream-u16-ret: func() -> stream<u16>;
   stream-u32-ret: func() -> stream<u32>;