diff --git a/crates/wasi/src/preview2/pipe.rs b/crates/wasi/src/preview2/pipe.rs
index 02e2ca0962e2..34eb8a34f03a 100644
--- a/crates/wasi/src/preview2/pipe.rs
+++ b/crates/wasi/src/preview2/pipe.rs
@@ -666,10 +666,13 @@ mod test {
         assert_eq!(len, chunk.len());
         assert_eq!(state, StreamState::Open);
 
-        // But I expect this to block additional writes:
+        // It is possible for subsequent writes to be refused, but it is nondeterminstic because
+        // the worker task consuming them is in another thread:
         let (len, state) = writer.write(chunk.clone()).unwrap();
-        assert_eq!(len, 0);
         assert_eq!(state, StreamState::Open);
+        if !(len == 0 || len == chunk.len()) {
+            unreachable!()
+        }
 
         tokio::time::timeout(REASONABLE_DURATION, writer.ready())
             .await
diff --git a/crates/wasi/src/preview2/preview2/io.rs b/crates/wasi/src/preview2/preview2/io.rs
index ed03fa9e77b0..ad41d0c97628 100644
--- a/crates/wasi/src/preview2/preview2/io.rs
+++ b/crates/wasi/src/preview2/preview2/io.rs
@@ -412,7 +412,7 @@ pub mod sync {
             stream: OutputStream,
             bytes: Vec<u8>,
         ) -> Result<(u64, streams::StreamStatus), streams::Error> {
-            in_tokio(async { AsyncHost::write(self, stream, bytes).await })
+            in_tokio(async { AsyncHost::blocking_write(self, stream, bytes).await })
                 .map(|(a, b)| (a, b.into()))
                 .map_err(streams::Error::from)
         }