diff --git a/crdt-enc/src/utils/version_bytes.rs b/crdt-enc/src/utils/version_bytes.rs
index 8d035a0..9e09ef0 100644
--- a/crdt-enc/src/utils/version_bytes.rs
+++ b/crdt-enc/src/utils/version_bytes.rs
@@ -285,8 +285,6 @@ impl<'a> Buf for VersionBytesBuf<'a> {
     }
 
     fn chunks_vectored<'b>(&'b self, dst: &mut [IoSlice<'b>]) -> usize {
-        // TODO: TESTING!
-
         if dst.len() == 0 {
             return 0;
         }
@@ -302,7 +300,7 @@ impl<'a> Buf for VersionBytesBuf<'a> {
             }
         } else {
             let pos = self.pos - VERSION_LEN;
-            if self.content.len() <= pos {
+            if self.content.len() == pos {
                 0
             } else {
                 dst[0] = IoSlice::new(&self.content[pos..]);
diff --git a/crdt-enc/tests/version_box_buf.rs b/crdt-enc/tests/version_box_buf.rs
new file mode 100644
index 0000000..84781b8
--- /dev/null
+++ b/crdt-enc/tests/version_box_buf.rs
@@ -0,0 +1,140 @@
+use bytes::Buf;
+use crdt_enc::utils::VersionBytesBuf;
+use std::io::IoSlice;
+use uuid::Uuid;
+
+const UUID: Uuid = Uuid::from_u128(0xd8d2cf50_a5c6_433b_98e6_8c268fd84fa0);
+
+#[test]
+fn simple() {
+    let mut buf = VersionBytesBuf::new(UUID, &[1, 2, 3]);
+    assert_eq!(buf.remaining(), 16 + 3);
+
+    let chunk = buf.chunk();
+    assert_eq!(chunk.len(), 16);
+    assert_eq!(chunk, UUID.as_bytes());
+
+    buf.advance(16);
+
+    assert_eq!(buf.remaining(), 3);
+
+    let chunk = buf.chunk();
+    assert_eq!(chunk.len(), 3);
+    assert_eq!(chunk, [1, 2, 3]);
+
+    buf.advance(3);
+
+    assert_eq!(buf.remaining(), 0);
+
+    // advance by 0 should never panic
+    buf.advance(0);
+
+    assert_eq!(buf.remaining(), 0);
+}
+
+#[test]
+fn unaligned_advance() {
+    let mut buf = VersionBytesBuf::new(UUID, &[1, 2, 3]);
+
+    buf.advance(4);
+
+    assert_eq!(buf.remaining(), 12 + 3);
+
+    let chunk = buf.chunk();
+    assert_eq!(chunk.len(), 12);
+    assert_eq!(chunk, &UUID.as_bytes()[4..]);
+
+    buf.advance(12 + 1);
+
+    assert_eq!(buf.remaining(), 2);
+
+    let chunk = buf.chunk();
+    assert_eq!(chunk.len(), 2);
+    assert_eq!(chunk, [2, 3]);
+
+    buf.advance(2);
+
+    assert_eq!(buf.remaining(), 0);
+
+    // advance by 0 should never panic
+    buf.advance(0);
+
+    assert_eq!(buf.remaining(), 0);
+}
+
+#[test]
+#[should_panic]
+fn out_of_bounds_advance() {
+    let mut buf = VersionBytesBuf::new(UUID, &[1, 2, 3]);
+    buf.advance(16 + 3 + 1);
+}
+
+#[test]
+fn vectored() {
+    let mut buf = VersionBytesBuf::new(UUID, &[1, 2, 3]);
+
+    let mut io_slice = [];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 0);
+
+    let mut io_slice = [IoSlice::new(&[99, 98])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 1);
+    assert_eq!(io_slice[0].as_ref(), UUID.as_bytes());
+
+    let mut io_slice = [IoSlice::new(&[99, 98]), IoSlice::new(&[97, 96])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 2);
+    assert_eq!(io_slice[0].as_ref(), UUID.as_bytes());
+    assert_eq!(io_slice[1].as_ref(), [1, 2, 3]);
+
+    let mut io_slice = [
+        IoSlice::new(&[99, 98]),
+        IoSlice::new(&[97, 96]),
+        IoSlice::new(&[95, 94]),
+    ];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 2);
+    assert_eq!(io_slice[0].as_ref(), UUID.as_bytes());
+    assert_eq!(io_slice[1].as_ref(), [1, 2, 3]);
+    assert_eq!(io_slice[2].as_ref(), [95, 94]);
+
+    buf.advance(5);
+
+    let mut io_slice = [IoSlice::new(&[99, 98])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 1);
+    assert_eq!(io_slice[0].as_ref(), &UUID.as_bytes()[5..]);
+
+    let mut io_slice = [IoSlice::new(&[99, 98]), IoSlice::new(&[97, 96])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 2);
+    assert_eq!(io_slice[0].as_ref(), &UUID.as_bytes()[5..]);
+    assert_eq!(io_slice[1].as_ref(), [1, 2, 3]);
+
+    let mut io_slice = [
+        IoSlice::new(&[99, 98]),
+        IoSlice::new(&[97, 96]),
+        IoSlice::new(&[95, 94]),
+    ];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 2);
+    assert_eq!(io_slice[0].as_ref(), &UUID.as_bytes()[5..]);
+    assert_eq!(io_slice[1].as_ref(), [1, 2, 3]);
+    assert_eq!(io_slice[2].as_ref(), [95, 94]);
+
+    buf.advance(11 + 1);
+
+    let mut io_slice = [IoSlice::new(&[99, 98])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 1);
+    assert_eq!(io_slice[0].as_ref(), [2, 3]);
+
+    let mut io_slice = [IoSlice::new(&[99, 98]), IoSlice::new(&[97, 96])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 1);
+    assert_eq!(io_slice[0].as_ref(), [2, 3]);
+    assert_eq!(io_slice[1].as_ref(), [97, 96]);
+
+    buf.advance(2);
+
+    let mut io_slice = [IoSlice::new(&[99, 98])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 0);
+    assert_eq!(io_slice[0].as_ref(), [99, 98]);
+
+    let mut io_slice = [IoSlice::new(&[99, 98]), IoSlice::new(&[97, 96])];
+    assert_eq!(buf.chunks_vectored(&mut io_slice), 0);
+    assert_eq!(io_slice[0].as_ref(), [99, 98]);
+    assert_eq!(io_slice[1].as_ref(), [97, 96]);
+}