diff --git a/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs b/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs
index 6407a32f3c..3246b5e505 100644
--- a/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs
+++ b/crates/test-programs/wasi-tests/src/bin/poll_oneoff.rs
@@ -55,7 +55,10 @@ unsafe fn test_timeout() {
         event.userdata, CLOCK_ID,
         "the event.userdata should contain clock_id specified by the user"
     );
-    assert!(after - before >= timeout, "poll_oneoff should sleep for the specified interval");
+    assert!(
+        after - before >= timeout,
+        "poll_oneoff should sleep for the specified interval"
+    );
 }
 
 // Like test_timeout, but uses `CLOCKID_REALTIME`, as WASI libc's sleep
@@ -90,20 +93,22 @@ unsafe fn test_sleep() {
         event.userdata, CLOCK_ID,
         "the event.userdata should contain clock_id specified by the user"
     );
-    assert!(after - before >= timeout, "poll_oneoff should sleep for the specified interval");
+    assert!(
+        after - before >= timeout,
+        "poll_oneoff should sleep for the specified interval"
+    );
 }
 
-unsafe fn test_fd_readwrite(fd: wasi::Fd, error_code: wasi::Errno) {
-    let fd_readwrite = wasi::SubscriptionFdReadwrite {
-        file_descriptor: fd,
-    };
+unsafe fn test_fd_readwrite(readable_fd: wasi::Fd, writable_fd: wasi::Fd, error_code: wasi::Errno) {
     let r#in = [
         wasi::Subscription {
             userdata: 1,
             u: wasi::SubscriptionU {
                 tag: wasi::EVENTTYPE_FD_READ,
                 u: wasi::SubscriptionUU {
-                    fd_read: fd_readwrite,
+                    fd_read: wasi::SubscriptionFdReadwrite {
+                        file_descriptor: readable_fd,
+                    },
                 },
             },
         },
@@ -112,7 +117,9 @@ unsafe fn test_fd_readwrite(fd: wasi::Fd, error_code: wasi::Errno) {
             u: wasi::SubscriptionU {
                 tag: wasi::EVENTTYPE_FD_WRITE,
                 u: wasi::SubscriptionUU {
-                    fd_write: fd_readwrite,
+                    fd_write: wasi::SubscriptionFdReadwrite {
+                        file_descriptor: writable_fd,
+                    },
                 },
             },
         },
@@ -143,26 +150,43 @@ unsafe fn test_fd_readwrite(fd: wasi::Fd, error_code: wasi::Errno) {
 
 unsafe fn test_fd_readwrite_valid_fd(dir_fd: wasi::Fd) {
     // Create a file in the scratch directory.
-    let file_fd = wasi::path_open(
+    let readable_fd = wasi::path_open(
         dir_fd,
         0,
-        "file",
+        "readable_file",
         wasi::OFLAGS_CREAT,
-        wasi::RIGHTS_FD_READ | wasi::RIGHTS_FD_WRITE | wasi::RIGHTS_POLL_FD_READWRITE,
+        wasi::RIGHTS_FD_READ | wasi::RIGHTS_POLL_FD_READWRITE,
         0,
         0,
     )
-    .expect("opening a file");
+    .expect("opening a readable file");
     assert_gt!(
-        file_fd,
+        readable_fd,
+        libc::STDERR_FILENO as wasi::Fd,
+        "file descriptor range check",
+    );
+    // Create a file in the scratch directory.
+    let writable_fd = wasi::path_open(
+        dir_fd,
+        0,
+        "writable_file",
+        wasi::OFLAGS_CREAT,
+        wasi::RIGHTS_FD_WRITE | wasi::RIGHTS_POLL_FD_READWRITE,
+        0,
+        0,
+    )
+    .expect("opening a writable file");
+    assert_gt!(
+        writable_fd,
         libc::STDERR_FILENO as wasi::Fd,
         "file descriptor range check",
     );
 
-    test_fd_readwrite(file_fd, wasi::ERRNO_SUCCESS);
+    test_fd_readwrite(readable_fd, writable_fd, wasi::ERRNO_SUCCESS);
 
-    wasi::fd_close(file_fd).expect("closing a file");
-    wasi::path_unlink_file(dir_fd, "file").expect("removing a file");
+    wasi::fd_close(readable_fd).expect("closing readable_file");
+    wasi::path_unlink_file(dir_fd, "readable_file").expect("removing readable_file");
+    wasi::path_unlink_file(dir_fd, "writable_file").expect("removing writable_file");
 }
 
 unsafe fn test_fd_readwrite_invalid_fd() {