diff --git a/librustzcash-wrapper/src/lib.rs b/librustzcash-wrapper/src/lib.rs
index a0e98b6..3209737 100644
--- a/librustzcash-wrapper/src/lib.rs
+++ b/librustzcash-wrapper/src/lib.rs
@@ -1445,9 +1445,10 @@ pub extern "C" fn rust_wrapper_read_sapling_witness(
     out: *mut u8,
     out_len: &mut usize
     ){
-    let tree_in: Vec<u8> = marshall_from_haskell_var(tree, tree_len, RW);
-    let tree_reader = Cursor::new(tree_in);
-    let ct: CommitmentTree<Node, SAPLING_DEPTH> = read_commitment_tree(tree_reader).unwrap();
+    let tree_in: Hfrontier = marshall_from_haskell_var(tree, tree_len, RW);
+    let leaf = Node::from_bytes(to_array(tree_in.leaf.bytes)).unwrap();
+    let frontier: Frontier<Node, SAPLING_DEPTH> = Frontier::from_parts(Position::from(tree_in.position), leaf, tree_in.ommers.iter().map(|x| Node::from_bytes(to_array(x.clone())).unwrap() ).collect()).unwrap();
+    let ct: CommitmentTree<Node, SAPLING_DEPTH> = CommitmentTree::from_frontier(&frontier);
     let inc_wit = IncrementalWitness::from_tree(ct);
     let mut out_bytes: Vec<u8> = Vec::new();
     let result = write_incremental_witness(&inc_wit, &mut out_bytes);
diff --git a/src/C/Zcash.chs b/src/C/Zcash.chs
index ab4bd54..71c73e5 100644
--- a/src/C/Zcash.chs
+++ b/src/C/Zcash.chs
@@ -212,7 +212,7 @@ import ZcashHaskell.Types
 #}
 
 {# fun unsafe rust_wrapper_read_sapling_witness as rustWrapperReadSaplingWitness
-     { toBorshVar* `BS.ByteString'&
+     { toBorshVar* `SaplingFrontier'&
      , getVarBuffer `Buffer HexString'&
      }
   -> `()'
diff --git a/src/ZcashHaskell/Sapling.hs b/src/ZcashHaskell/Sapling.hs
index 4b7c286..e15bf4f 100644
--- a/src/ZcashHaskell/Sapling.hs
+++ b/src/ZcashHaskell/Sapling.hs
@@ -210,15 +210,13 @@ updateSaplingCommitmentTree tree cmu =
       rustWrapperReadSaplingCommitmentTree tree (hexBytes cmu)
 
 -- | Get the Sapling incremental witness from a commitment tree
-getSaplingWitness :: SaplingCommitmentTree -> Maybe SaplingWitness
+getSaplingWitness :: SaplingFrontier -> Maybe SaplingWitness
 getSaplingWitness tree =
   if BS.length (hexBytes wit) > 1
     then Just $ SaplingWitness wit
     else Nothing
   where
-    wit =
-      withPureBorshVarBuffer $
-      rustWrapperReadSaplingWitness (hexBytes $ sapTree tree)
+    wit = withPureBorshVarBuffer $ rustWrapperReadSaplingWitness tree
 
 -- | Get the Sapling note position from a witness
 getSaplingNotePosition :: SaplingWitness -> Integer