diff --git a/libCacheSim/cache/prefetch/Mithril.c b/libCacheSim/cache/prefetch/Mithril.c
index ff1a4726..6f237854 100644
--- a/libCacheSim/cache/prefetch/Mithril.c
+++ b/libCacheSim/cache/prefetch/Mithril.c
@@ -340,7 +340,7 @@ void Mithril_prefetch(cache_t *cache, const request_t *req) {
               (Mithril_params->pf_list_size + 1);
 
   request_t *new_req = my_malloc(request_t);
-  memcpy(new_req, req, sizeof(request_t));
+  copy_request(new_req, req);
 
   if (prefetch_table_index) {
     int i;
@@ -497,7 +497,7 @@ static inline bool _Mithril_check_sequential(cache_t *cache,
   if (Mithril_params->sequential_K == 0) return FALSE;
 
   request_t *new_req = my_malloc(request_t);
-  memcpy(new_req, req, sizeof(request_t));
+  copy_request(new_req, req);
   bool is_sequential = TRUE;
   gint sequential_K = Mithril_params->sequential_K;
   if (sequential_K == -1) { /* when use AMP, this is -1 */
diff --git a/libCacheSim/cache/prefetch/PG.c b/libCacheSim/cache/prefetch/PG.c
index 0eea9f5b..db16c0e2 100644
--- a/libCacheSim/cache/prefetch/PG.c
+++ b/libCacheSim/cache/prefetch/PG.c
@@ -162,7 +162,7 @@ void PG_prefetch(cache_t *cache, const request_t *req) {
   if (prefetch_list) {
     GList *node = prefetch_list;
     request_t *new_req = my_malloc(request_t);
-    memcpy(new_req, req, sizeof(request_t));
+    copy_request(new_req, req);
     while (node) {
       new_req->obj_id = GPOINTER_TO_INT(node->data);
       new_req->obj_size =
diff --git a/libCacheSim/include/libCacheSim/request.h b/libCacheSim/include/libCacheSim/request.h
index a32c4337..23cc7298 100644
--- a/libCacheSim/include/libCacheSim/request.h
+++ b/libCacheSim/include/libCacheSim/request.h
@@ -87,7 +87,7 @@ static inline request_t *new_request(void) {
  * @param req_dest
  * @param req_src
  */
-static inline void copy_request(request_t *req_dest, request_t *req_src) {
+static inline void copy_request(request_t *req_dest, const request_t *req_src) {
   memcpy(req_dest, req_src, sizeof(request_t));
 }
 
@@ -96,7 +96,7 @@ static inline void copy_request(request_t *req_dest, request_t *req_src) {
  * @param req
  * @return
  */
-static inline request_t *clone_request(request_t *req) {
+static inline request_t *clone_request(const request_t *req) {
   request_t *req_new = my_malloc(request_t);
   copy_request(req_new, req);
   return req_new;