diff --git a/include/mimalloc.h b/include/mimalloc.h
index bc817f54..4611dac0 100644
--- a/include/mimalloc.h
+++ b/include/mimalloc.h
@@ -230,6 +230,7 @@ mi_decl_export bool mi_heap_visit_blocks(const mi_heap_t* heap, bool visit_all_b
 mi_decl_export bool mi_is_in_heap_region(const void* p) mi_attr_noexcept;
 mi_decl_export int  mi_reserve_huge_os_pages(size_t pages, double max_secs, size_t* pages_reserved) mi_attr_noexcept;
 mi_decl_export bool mi_is_redirected() mi_attr_noexcept;
+mi_decl_export void mi_mem_clear(void *p, size_t);
 
 // ------------------------------------------------------
 // Convenience
diff --git a/src/memory.c b/src/memory.c
index dd03cf95..b5f81268 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -130,6 +130,17 @@ bool mi_is_in_heap_region(const void* p) mi_attr_noexcept {
   return false;
 }
 
+// In secure mode, volatile function pointer is used
+// to discard eventual compiler optimization
+void mi_mem_clear(void *p, size_t len) {
+  if (MI_SECURE>=1) {
+    void *(*volatile mem_clear)(void *, int, size_t) = memset;
+    (void)mem_clear(p, 0, len);
+  } else {
+    (void)memset(p, 0, len);
+  }
+}
+
 
 /* ----------------------------------------------------------------------------
 Commit from a region
diff --git a/test/test-stress.c b/test/test-stress.c
index b6ceaa0a..ef4b8d7e 100644
--- a/test/test-stress.c
+++ b/test/test-stress.c
@@ -248,7 +248,7 @@ static void* thread_entry(void* param) {
 
 static void run_os_threads(size_t nthreads) {
   pthread_t* threads = (pthread_t*)custom_malloc(nthreads*sizeof(pthread_t));
-  memset(threads, 0, sizeof(pthread_t)*nthreads);
+  mi_mem_clear(threads, sizeof(pthread_t)*nthreads);
   //pthread_setconcurrency(nthreads);
   for (uintptr_t i = 0; i < nthreads; i++) {
     pthread_create(&threads[i], NULL, &thread_entry, (void*)i);