diff --git a/src/key_io.cpp b/src/key_io.cpp
index 44f56e44a..86bec602e 100644
--- a/src/key_io.cpp
+++ b/src/key_io.cpp
@@ -70,13 +70,15 @@ static size_t GetReceiverLen(const void* ua, size_t index)
 
 class CopyDataForReceiver {
     unsigned char* data;
+    size_t length;
 
 public:
-    CopyDataForReceiver(unsigned char* data) : data(data) {}
+    CopyDataForReceiver(unsigned char* data, size_t length) : data(data), length(length) {}
 
     void operator()(const libzcash::SaplingPaymentAddress &zaddr) const {
         CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
         ss << zaddr;
+        assert(length == ss.size());
         memcpy(data, ss.data(), ss.size());
     }
 
@@ -96,10 +98,10 @@ public:
 /**
  * `data` MUST be the correct length for the receiver at this index.
  */
-static void GetReceiver(const void* ua, size_t index, unsigned char* data)
+static void GetReceiver(const void* ua, size_t index, unsigned char* data, size_t length)
 {
     std::visit(
-        CopyDataForReceiver(data),
+        CopyDataForReceiver(data, length),
         reinterpret_cast<const libzcash::UnifiedAddress*>(ua)->GetReceiversAsParsed()[index]);
 }
 
diff --git a/src/rust/include/rust/address.h b/src/rust/include/rust/address.h
index ab2f94a30..ab9e8750a 100644
--- a/src/rust/include/rust/address.h
+++ b/src/rust/include/rust/address.h
@@ -17,7 +17,7 @@ typedef bool (*unknown_receiver_t)(
     size_t len);
 typedef uint8_t (*get_typecode_t)(const void* ua, size_t index);
 typedef size_t (*get_receiver_len_t)(const void* ua, size_t index);
-typedef void (*get_receiver_t)(const void* ua, size_t index, unsigned char* data);
+typedef void (*get_receiver_t)(const void* ua, size_t index, unsigned char* data, size_t length);
 
 /// Parses a unified address from the given string.
 bool zcash_address_parse_unified(
diff --git a/src/rust/src/address_ffi.rs b/src/rust/src/address_ffi.rs
index c1ab48b77..e0bc66ba0 100644
--- a/src/rust/src/address_ffi.rs
+++ b/src/rust/src/address_ffi.rs
@@ -21,7 +21,7 @@ pub type GetTypecodeCb = unsafe extern "C" fn(ua: Option<UnifiedAddressObj>, ind
 pub type GetReceiverLenCb =
     unsafe extern "C" fn(ua: Option<UnifiedAddressObj>, index: usize) -> usize;
 pub type GetReceiverDataCb =
-    unsafe extern "C" fn(ua: Option<UnifiedAddressObj>, index: usize, data: *mut u8);
+    unsafe extern "C" fn(ua: Option<UnifiedAddressObj>, index: usize, data: *mut u8, length: usize);
 
 fn network_from_cstr(network: *const c_char) -> Option<Network> {
     match unsafe { CStr::from_ptr(network) }.to_str().unwrap() {
@@ -169,7 +169,7 @@ pub extern "C" fn zcash_address_serialize_unified(
                     // TODO: Replace with Orchard support.
                     let data_len = unsafe { (receiver_len_cb.unwrap())(ua_obj, i) };
                     let mut data = vec![0; data_len];
-                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr()) };
+                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr(), data_len) };
                     unified::Receiver::Unknown {
                         typecode: 0x03,
                         data,
@@ -177,23 +177,23 @@ pub extern "C" fn zcash_address_serialize_unified(
                 }
                 unified::Typecode::Sapling => {
                     let mut data = [0; 43];
-                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr()) };
+                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr(), data.len()) };
                     unified::Receiver::Sapling(data)
                 }
                 unified::Typecode::P2sh => {
                     let mut data = [0; 20];
-                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr()) };
+                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr(), data.len()) };
                     unified::Receiver::P2sh(data)
                 }
                 unified::Typecode::P2pkh => {
                     let mut data = [0; 20];
-                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr()) };
+                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr(), data.len()) };
                     unified::Receiver::P2pkh(data)
                 }
                 unified::Typecode::Unknown(typecode) => {
                     let data_len = unsafe { (receiver_len_cb.unwrap())(ua_obj, i) };
                     let mut data = vec![0; data_len];
-                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr()) };
+                    unsafe { (receiver_cb.unwrap())(ua_obj, i, data.as_mut_ptr(), data_len) };
                     unified::Receiver::Unknown { typecode, data }
                 }
             },