diff --git a/examples/unix/c11/z_queryable_attachment.c b/examples/unix/c11/z_queryable_attachment.c
index e223143bb..3e0b7062e 100644
--- a/examples/unix/c11/z_queryable_attachment.c
+++ b/examples/unix/c11/z_queryable_attachment.c
@@ -97,7 +97,7 @@ void query_handler(z_loaned_query_t *query, void *ctx) {
     z_bytes_empty(&reply_attachment);
     kv_pair_t kvs[1];
     z_string_from_str(&kvs[0].key, "reply_key", NULL, NULL);
-    z_string_from_str(&kvs[1].key, "reply_value", NULL, NULL);
+    z_string_from_str(&kvs[0].value, "reply_value", NULL, NULL);
     z_bytes_writer_t writer = z_bytes_get_writer(z_loan_mut(reply_attachment));
     z_bytes_writer_serialize_sequence_begin(&writer, 1);
     z_bytes_writer_serialize_string(&writer, z_loan(kvs[0].key));
diff --git a/src/api/serialization.c b/src/api/serialization.c
index 6df8469bc..b17faf4f3 100644
--- a/src/api/serialization.c
+++ b/src/api/serialization.c
@@ -57,7 +57,7 @@ z_result_t z_bytes_writer_serialize_slice(z_bytes_writer_t *writer, const z_loan
 }
 
 z_result_t z_bytes_reader_deserialize_slice(z_bytes_reader_t *reader, z_owned_slice_t *val) {
-    size_t len;
+    size_t len = 0;
     _Z_RETURN_IF_ERR(z_bytes_reader_deserialize_sequence_begin(reader, &len));
     _Z_RETURN_IF_ERR(_z_slice_init(&val->_val, len));
     if (z_bytes_reader_read(reader, (uint8_t *)val->_val.start, len) != len) {