diff --git a/tests/rust/wasm32-wasip3/src/bin/filesystem-set-size.json b/tests/rust/wasm32-wasip3/src/bin/filesystem-set-size.json
new file mode 100644
index 00000000..ff216a75
--- /dev/null
+++ b/tests/rust/wasm32-wasip3/src/bin/filesystem-set-size.json
@@ -0,0 +1,3 @@
+{
+    "dirs": ["fs-tests.dir"]
+}
diff --git a/tests/rust/wasm32-wasip3/src/bin/filesystem-set-size.rs b/tests/rust/wasm32-wasip3/src/bin/filesystem-set-size.rs
new file mode 100644
index 00000000..8a54f08a
--- /dev/null
+++ b/tests/rust/wasm32-wasip3/src/bin/filesystem-set-size.rs
@@ -0,0 +1,130 @@
+use std::process;
+extern crate wit_bindgen;
+
+wit_bindgen::generate!({
+    inline: r"
+  package test:test;
+
+  world test {
+      include wasi:filesystem/imports@0.3.0-rc-2025-09-16;
+      include wasi:cli/command@0.3.0-rc-2025-09-16;
+  }
+",
+    additional_derives: [PartialEq, Eq, Hash, Clone],
+    // Work around https://github.com/bytecodealliance/wasm-tools/issues/2285.
+    features:["clocks-timezone"],
+    generate_all
+});
+
+use wasi::filesystem::types::Descriptor;
+use wasi::filesystem::types::{DescriptorFlags, ErrorCode, OpenFlags, PathFlags};
+
+async fn test_set_size(dir: &Descriptor) {
+    // set-size: async func(size: filesize) -> result<_, error-code>;
+    let open = |path: &str, oflags: OpenFlags, fdflags: DescriptorFlags| -> _ {
+        dir.open_at(PathFlags::empty(), path.to_string(), oflags, fdflags)
+    };
+    let open_r = |path: &str| -> _ { open(path, OpenFlags::empty(), DescriptorFlags::READ) };
+    let open_w = |path: &str| -> _ {
+        open(
+            path,
+            OpenFlags::empty(),
+            DescriptorFlags::READ | DescriptorFlags::WRITE,
+        )
+    };
+    let creat = |path: &str| -> _ {
+        open(
+            path,
+            OpenFlags::CREATE | OpenFlags::EXCLUSIVE,
+            DescriptorFlags::READ | DescriptorFlags::WRITE,
+        )
+    };
+    let trunc = |path: &str| -> _ {
+        open(
+            path,
+            OpenFlags::TRUNCATE,
+            DescriptorFlags::READ | DescriptorFlags::WRITE,
+        )
+    };
+    let rm = |path: &str| dir.unlink_file_at(path.to_string());
+
+    let c = creat("c.cleanup").await.unwrap();
+    assert_eq!(c.stat().await.unwrap().size, 0);
+    c.set_size(42).await.unwrap();
+    // Setting size is visible immediately.
+    assert_eq!(c.stat().await.unwrap().size, 42);
+
+    let c = open_w("c.cleanup").await.unwrap();
+    let r = open_r("c.cleanup").await.unwrap();
+    assert_eq!(c.stat().await.unwrap().size, 42);
+    assert_eq!(r.stat().await.unwrap().size, 42);
+    c.set_size(69).await.unwrap();
+    assert_eq!(c.stat().await.unwrap().size, 69);
+    assert_eq!(r.stat().await.unwrap().size, 69);
+
+    let c = trunc("c.cleanup").await.unwrap();
+    assert_eq!(c.stat().await.unwrap().size, 0);
+    assert_eq!(r.stat().await.unwrap().size, 0);
+
+    // https://github.com/WebAssembly/WASI/issues/712
+    match r.set_size(100).await {
+        Ok(()) => {
+            panic!("set-size succeeded on read-only descriptor");
+        }
+        Err(ErrorCode::Invalid | ErrorCode::BadDescriptor | ErrorCode::Access) => {}
+        Err(err) => {
+            panic!("unexpected err: {}", err)
+        }
+    };
+
+    // https://github.com/WebAssembly/WASI/issues/712
+    match c.set_size(u64::MAX).await {
+        Ok(()) => {
+            panic!("set-size(-1) succeeded");
+        }
+        Err(ErrorCode::Invalid | ErrorCode::FileTooLarge) => {}
+        Err(err) => {
+            panic!("unexpected err: {}", err)
+        }
+    };
+
+    match rm("c.cleanup").await {
+        Ok(()) => {
+            // We still have `c` and `r` open, which refer to the file,
+            // but we can still stat our descriptors, call `set-size` on
+            // it, and so on.
+            assert_eq!(c.stat().await.unwrap().size, 0);
+            c.set_size(42).await.unwrap();
+            assert_eq!(c.stat().await.unwrap().size, 42);
+            assert_eq!(r.stat().await.unwrap().size, 42);
+        }
+        Err(ErrorCode::Busy) => {
+            // Otherwise if we're on Windows we are unable to remove the
+            // file while descriptors are open.
+        }
+        Err(err) => {
+            panic!("unexpected err: {}", err)
+        }
+    }
+}
+
+struct Component;
+export!(Component);
+impl exports::wasi::cli::run::Guest for Component {
+    async fn run() -> Result<(), ()> {
+        match &wasi::filesystem::preopens::get_directories()[..] {
+            [(dir, dirname)] if dirname == "fs-tests.dir" => {
+                test_set_size(dir).await;
+            }
+            [..] => {
+                eprintln!("usage: run with one open dir named 'fs-tests.dir'");
+                process::exit(1)
+            }
+        };
+        Ok(())
+    }
+}
+
+fn main() {
+    unreachable!("main is a stub");
+}