diff --git a/async-usercalls/src/alloc/mod.rs b/async-usercalls/src/alloc/mod.rs
index ab1085c04..d1a1abff1 100644
--- a/async-usercalls/src/alloc/mod.rs
+++ b/async-usercalls/src/alloc/mod.rs
@@ -3,13 +3,11 @@ use std::os::fortanix_sgx::usercalls::raw::ByteBuffer;
 
 mod allocator;
 mod bitmap;
-mod io_bufs;
 mod slab;
 #[cfg(test)]
 mod tests;
 
 use self::allocator::{LocalAllocator, SharedAllocator};
-pub use self::io_bufs::{ReadBuffer, UserBuf, WriteBuffer};
 pub use self::slab::{User, UserSafeExt};
 
 /// Allocates a slice of bytes in userspace that is at least as large as `size`.
diff --git a/async-usercalls/src/alloc/tests.rs b/async-usercalls/src/alloc/tests.rs
index da4e8b3d3..0d9906ab9 100644
--- a/async-usercalls/src/alloc/tests.rs
+++ b/async-usercalls/src/alloc/tests.rs
@@ -1,6 +1,5 @@
 use super::allocator::SharedAllocator;
 use super::bitmap::*;
-use super::io_bufs::{ReadBuffer, UserBuf, WriteBuffer};
 use super::slab::{BufSlab, Slab, SlabAllocator, User};
 use crossbeam_channel as mpmc;
 use std::collections::HashSet;
@@ -262,62 +261,3 @@ fn alloc_buf_size() {
     let b = super::alloc_buf(8 * 1024);
     assert_eq!(b.len(), 8 * 1024);
 }
-
-#[test]
-fn write_buffer_basic() {
-    const LENGTH: usize = 1024;
-    let mut write_buffer = WriteBuffer::new(super::alloc_buf(1024));
-
-    let buf = vec![0u8; LENGTH];
-    assert_eq!(write_buffer.write(&buf), LENGTH);
-    assert_eq!(write_buffer.write(&buf), 0);
-
-    let chunk = write_buffer.consumable_chunk().unwrap();
-    write_buffer.consume(chunk, 200);
-    assert_eq!(write_buffer.write(&buf), 200);
-    assert_eq!(write_buffer.write(&buf), 0);
-}
-
-#[test]
-#[should_panic]
-fn call_consumable_chunk_twice() {
-    const LENGTH: usize = 1024;
-    let mut write_buffer = WriteBuffer::new(super::alloc_buf(1024));
-
-    let buf = vec![0u8; LENGTH];
-    assert_eq!(write_buffer.write(&buf), LENGTH);
-    assert_eq!(write_buffer.write(&buf), 0);
-
-    let chunk1 = write_buffer.consumable_chunk().unwrap();
-    let _ = write_buffer.consumable_chunk().unwrap();
-    drop(chunk1);
-}
-
-#[test]
-#[should_panic]
-fn consume_wrong_buf() {
-    const LENGTH: usize = 1024;
-    let mut write_buffer = WriteBuffer::new(super::alloc_buf(1024));
-
-    let buf = vec![0u8; LENGTH];
-    assert_eq!(write_buffer.write(&buf), LENGTH);
-    assert_eq!(write_buffer.write(&buf), 0);
-
-    let unrelated_buf: UserBuf = super::alloc_buf(512).into();
-    write_buffer.consume(unrelated_buf, 100);
-}
-
-#[test]
-fn read_buffer_basic() {
-    let mut buf = super::alloc_buf(64);
-    const DATA: &'static [u8] = b"hello";
-    buf[0..DATA.len()].copy_from_enclave(DATA);
-
-    let mut read_buffer = ReadBuffer::new(buf, DATA.len());
-    assert_eq!(read_buffer.len(), DATA.len());
-    assert_eq!(read_buffer.remaining_bytes(), DATA.len());
-    let mut buf = [0u8; 8];
-    assert_eq!(read_buffer.read(&mut buf), DATA.len());
-    assert_eq!(read_buffer.remaining_bytes(), 0);
-    assert_eq!(&buf, b"hello\0\0\0");
-}
diff --git a/async-usercalls/src/alloc/io_bufs.rs b/async-usercalls/src/io_bufs.rs
similarity index 99%
rename from async-usercalls/src/alloc/io_bufs.rs
rename to async-usercalls/src/io_bufs.rs
index 3880e763e..7eb6b6e0c 100644
--- a/async-usercalls/src/alloc/io_bufs.rs
+++ b/async-usercalls/src/io_bufs.rs
@@ -1,4 +1,4 @@
-use super::slab::User;
+use crate::alloc::User;
 use std::cell::UnsafeCell;
 use std::cmp;
 use std::io::IoSlice;
diff --git a/async-usercalls/src/lib.rs b/async-usercalls/src/lib.rs
index e3a9e5d31..ab2b9e01f 100644
--- a/async-usercalls/src/lib.rs
+++ b/async-usercalls/src/lib.rs
@@ -15,6 +15,7 @@ mod batch_drop;
 mod callback;
 mod duplicated;
 mod hacks;
+mod io_bufs;
 mod provider_api;
 mod provider_core;
 mod queues;
@@ -22,9 +23,10 @@ mod raw;
 #[cfg(test)]
 mod tests;
 
-pub use self::alloc::{alloc_buf, alloc_byte_buffer, ReadBuffer, User, UserBuf, UserSafeExt, WriteBuffer};
+pub use self::alloc::{alloc_buf, alloc_byte_buffer, User, UserSafeExt};
 pub use self::batch_drop::batch_drop;
 pub use self::callback::CbFn;
+pub use self::io_bufs::{ReadBuffer, UserBuf, WriteBuffer};
 pub use self::raw::RawApi;
 
 use self::callback::*;
diff --git a/async-usercalls/src/provider_api.rs b/async-usercalls/src/provider_api.rs
index 087a22ee7..0dff9f7f2 100644
--- a/async-usercalls/src/provider_api.rs
+++ b/async-usercalls/src/provider_api.rs
@@ -1,6 +1,7 @@
-use crate::alloc::{alloc_buf, alloc_byte_buffer, User, UserBuf};
+use crate::alloc::{alloc_buf, alloc_byte_buffer, User};
 use crate::batch_drop;
 use crate::hacks::{new_std_listener, new_std_stream, MakeSend};
+use crate::io_bufs::UserBuf;
 use crate::raw::RawApi;
 use crate::{AsyncUsercallProvider, CancelHandle};
 use fortanix_sgx_abi::Fd;
diff --git a/async-usercalls/src/tests.rs b/async-usercalls/src/tests.rs
index a72d6c7d8..406c82443 100644
--- a/async-usercalls/src/tests.rs
+++ b/async-usercalls/src/tests.rs
@@ -194,6 +194,65 @@ fn safe_alloc_free() {
 
 unsafe impl Send for MakeSend<StdUser<[u8]>> {}
 
+#[test]
+fn write_buffer_basic() {
+    const LENGTH: usize = 1024;
+    let mut write_buffer = WriteBuffer::new(super::alloc_buf(1024));
+
+    let buf = vec![0u8; LENGTH];
+    assert_eq!(write_buffer.write(&buf), LENGTH);
+    assert_eq!(write_buffer.write(&buf), 0);
+
+    let chunk = write_buffer.consumable_chunk().unwrap();
+    write_buffer.consume(chunk, 200);
+    assert_eq!(write_buffer.write(&buf), 200);
+    assert_eq!(write_buffer.write(&buf), 0);
+}
+
+#[test]
+#[should_panic]
+fn call_consumable_chunk_twice() {
+    const LENGTH: usize = 1024;
+    let mut write_buffer = WriteBuffer::new(super::alloc_buf(1024));
+
+    let buf = vec![0u8; LENGTH];
+    assert_eq!(write_buffer.write(&buf), LENGTH);
+    assert_eq!(write_buffer.write(&buf), 0);
+
+    let chunk1 = write_buffer.consumable_chunk().unwrap();
+    let _ = write_buffer.consumable_chunk().unwrap();
+    drop(chunk1);
+}
+
+#[test]
+#[should_panic]
+fn consume_wrong_buf() {
+    const LENGTH: usize = 1024;
+    let mut write_buffer = WriteBuffer::new(super::alloc_buf(1024));
+
+    let buf = vec![0u8; LENGTH];
+    assert_eq!(write_buffer.write(&buf), LENGTH);
+    assert_eq!(write_buffer.write(&buf), 0);
+
+    let unrelated_buf: UserBuf = super::alloc_buf(512).into();
+    write_buffer.consume(unrelated_buf, 100);
+}
+
+#[test]
+fn read_buffer_basic() {
+    let mut buf = super::alloc_buf(64);
+    const DATA: &'static [u8] = b"hello";
+    buf[0..DATA.len()].copy_from_enclave(DATA);
+
+    let mut read_buffer = ReadBuffer::new(buf, DATA.len());
+    assert_eq!(read_buffer.len(), DATA.len());
+    assert_eq!(read_buffer.remaining_bytes(), DATA.len());
+    let mut buf = [0u8; 8];
+    assert_eq!(read_buffer.read(&mut buf), DATA.len());
+    assert_eq!(read_buffer.remaining_bytes(), 0);
+    assert_eq!(&buf, b"hello\0\0\0");
+}
+
 #[test]
 #[ignore]
 fn echo() {