diff --git a/src/alloc.c b/src/alloc.c
index 62e76e23..f0e31fdb 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -70,7 +70,7 @@ extern inline void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t siz
 }
 
 // allocate a small block
-extern inline mi_decl_restrict void* mi_heap_malloc_small(mi_heap_t* heap, size_t size) mi_attr_noexcept {
+extern inline mi_decl_nodiscard mi_decl_restrict void* mi_heap_malloc_small(mi_heap_t* heap, size_t size) mi_attr_noexcept {
   mi_assert(heap!=NULL);
   mi_assert(heap->thread_id == 0 || heap->thread_id == _mi_thread_id()); // heaps are thread local
   mi_assert(size <= MI_SMALL_SIZE_MAX);
@@ -91,12 +91,12 @@ extern inline mi_decl_restrict void* mi_heap_malloc_small(mi_heap_t* heap, size_
   return p;
 }
 
-extern inline mi_decl_restrict void* mi_malloc_small(size_t size) mi_attr_noexcept {
+extern inline mi_decl_nodiscard mi_decl_restrict void* mi_malloc_small(size_t size) mi_attr_noexcept {
   return mi_heap_malloc_small(mi_get_default_heap(), size);
 }
 
 // The main allocation function
-extern inline mi_decl_restrict void* mi_heap_malloc(mi_heap_t* heap, size_t size) mi_attr_noexcept {
+extern inline mi_decl_nodiscard mi_decl_restrict void* mi_heap_malloc(mi_heap_t* heap, size_t size) mi_attr_noexcept {
   if (mi_likely(size <= MI_SMALL_SIZE_MAX)) {
     return mi_heap_malloc_small(heap, size);
   }
@@ -115,7 +115,7 @@ extern inline mi_decl_restrict void* mi_heap_malloc(mi_heap_t* heap, size_t size
   }
 }
 
-extern inline mi_decl_restrict void* mi_malloc(size_t size) mi_attr_noexcept {
+extern inline mi_decl_nodiscard mi_decl_restrict void* mi_malloc(size_t size) mi_attr_noexcept {
   return mi_heap_malloc(mi_get_default_heap(), size);
 }
 
@@ -139,7 +139,7 @@ void _mi_block_zero_init(const mi_page_t* page, void* p, size_t size) {
 }
 
 // zero initialized small block
-mi_decl_restrict void* mi_zalloc_small(size_t size) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict void* mi_zalloc_small(size_t size) mi_attr_noexcept {
   void* p = mi_malloc_small(size);
   if (p != NULL) {
     _mi_block_zero_init(_mi_ptr_page(p), p, size);  // todo: can we avoid getting the page again?
@@ -155,11 +155,11 @@ void* _mi_heap_malloc_zero(mi_heap_t* heap, size_t size, bool zero) mi_attr_noex
   return p;
 }
 
-extern inline mi_decl_restrict void* mi_heap_zalloc(mi_heap_t* heap, size_t size) mi_attr_noexcept {
+extern inline mi_decl_nodiscard mi_decl_restrict void* mi_heap_zalloc(mi_heap_t* heap, size_t size) mi_attr_noexcept {
   return _mi_heap_malloc_zero(heap, size, true);
 }
 
-mi_decl_restrict void* mi_zalloc(size_t size) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict void* mi_zalloc(size_t size) mi_attr_noexcept {
   return mi_heap_zalloc(mi_get_default_heap(),size);
 }
 
@@ -552,7 +552,7 @@ static inline size_t _mi_usable_size(const void* p, const char* msg) mi_attr_noe
   }
 }
 
-size_t mi_usable_size(const void* p) mi_attr_noexcept {
+mi_decl_nodiscard size_t mi_usable_size(const void* p) mi_attr_noexcept {
   return _mi_usable_size(p, "mi_usable_size");
 }
 
@@ -596,24 +596,24 @@ void mi_free_aligned(void* p, size_t alignment) mi_attr_noexcept {
   mi_free(p);
 }
 
-extern inline mi_decl_restrict void* mi_heap_calloc(mi_heap_t* heap, size_t count, size_t size) mi_attr_noexcept {
+extern inline mi_decl_nodiscard mi_decl_restrict void* mi_heap_calloc(mi_heap_t* heap, size_t count, size_t size) mi_attr_noexcept {
   size_t total;
   if (mi_count_size_overflow(count,size,&total)) return NULL;
   return mi_heap_zalloc(heap,total);
 }
 
-mi_decl_restrict void* mi_calloc(size_t count, size_t size) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict void* mi_calloc(size_t count, size_t size) mi_attr_noexcept {
   return mi_heap_calloc(mi_get_default_heap(),count,size);
 }
 
 // Uninitialized `calloc`
-extern mi_decl_restrict void* mi_heap_mallocn(mi_heap_t* heap, size_t count, size_t size) mi_attr_noexcept {
+extern mi_decl_nodiscard mi_decl_restrict void* mi_heap_mallocn(mi_heap_t* heap, size_t count, size_t size) mi_attr_noexcept {
   size_t total;
   if (mi_count_size_overflow(count, size, &total)) return NULL;
   return mi_heap_malloc(heap, total);
 }
 
-mi_decl_restrict void* mi_mallocn(size_t count, size_t size) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict void* mi_mallocn(size_t count, size_t size) mi_attr_noexcept {
   return mi_heap_mallocn(mi_get_default_heap(),count,size);
 }
 
@@ -652,11 +652,11 @@ void* _mi_heap_realloc_zero(mi_heap_t* heap, void* p, size_t newsize, bool zero)
   return newp;
 }
 
-void* mi_heap_realloc(mi_heap_t* heap, void* p, size_t newsize) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_heap_realloc(mi_heap_t* heap, void* p, size_t newsize) mi_attr_noexcept {
   return _mi_heap_realloc_zero(heap, p, newsize, false);  
 }
 
-void* mi_heap_reallocn(mi_heap_t* heap, void* p, size_t count, size_t size) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_heap_reallocn(mi_heap_t* heap, void* p, size_t count, size_t size) mi_attr_noexcept {
   size_t total;
   if (mi_count_size_overflow(count, size, &total)) return NULL;
   return mi_heap_realloc(heap, p, total);
@@ -664,41 +664,41 @@ void* mi_heap_reallocn(mi_heap_t* heap, void* p, size_t count, size_t size) mi_a
 
 
 // Reallocate but free `p` on errors
-void* mi_heap_reallocf(mi_heap_t* heap, void* p, size_t newsize) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_heap_reallocf(mi_heap_t* heap, void* p, size_t newsize) mi_attr_noexcept {
   void* newp = mi_heap_realloc(heap, p, newsize);
   if (newp==NULL && p!=NULL) mi_free(p);
   return newp;
 }
 
-void* mi_heap_rezalloc(mi_heap_t* heap, void* p, size_t newsize) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_heap_rezalloc(mi_heap_t* heap, void* p, size_t newsize) mi_attr_noexcept {
   return _mi_heap_realloc_zero(heap, p, newsize, true);
 }
 
-void* mi_heap_recalloc(mi_heap_t* heap, void* p, size_t count, size_t size) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_heap_recalloc(mi_heap_t* heap, void* p, size_t count, size_t size) mi_attr_noexcept {
   size_t total;
   if (mi_count_size_overflow(count, size, &total)) return NULL;
   return mi_heap_rezalloc(heap, p, total);
 }
 
 
-void* mi_realloc(void* p, size_t newsize) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_realloc(void* p, size_t newsize) mi_attr_noexcept {
   return mi_heap_realloc(mi_get_default_heap(),p,newsize);
 }
 
-void* mi_reallocn(void* p, size_t count, size_t size) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_reallocn(void* p, size_t count, size_t size) mi_attr_noexcept {
   return mi_heap_reallocn(mi_get_default_heap(),p,count,size);
 }
 
 // Reallocate but free `p` on errors
-void* mi_reallocf(void* p, size_t newsize) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_reallocf(void* p, size_t newsize) mi_attr_noexcept {
   return mi_heap_reallocf(mi_get_default_heap(),p,newsize);
 }
 
-void* mi_rezalloc(void* p, size_t newsize) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_rezalloc(void* p, size_t newsize) mi_attr_noexcept {
   return mi_heap_rezalloc(mi_get_default_heap(), p, newsize);
 }
 
-void* mi_recalloc(void* p, size_t count, size_t size) mi_attr_noexcept {
+mi_decl_nodiscard void* mi_recalloc(void* p, size_t count, size_t size) mi_attr_noexcept {
   return mi_heap_recalloc(mi_get_default_heap(), p, count, size);
 }
 
@@ -709,7 +709,7 @@ void* mi_recalloc(void* p, size_t count, size_t size) mi_attr_noexcept {
 // ------------------------------------------------------
 
 // `strdup` using mi_malloc
-mi_decl_restrict char* mi_heap_strdup(mi_heap_t* heap, const char* s) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict char* mi_heap_strdup(mi_heap_t* heap, const char* s) mi_attr_noexcept {
   if (s == NULL) return NULL;
   size_t n = strlen(s);
   char* t = (char*)mi_heap_malloc(heap,n+1);
@@ -717,12 +717,12 @@ mi_decl_restrict char* mi_heap_strdup(mi_heap_t* heap, const char* s) mi_attr_no
   return t;
 }
 
-mi_decl_restrict char* mi_strdup(const char* s) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict char* mi_strdup(const char* s) mi_attr_noexcept {
   return mi_heap_strdup(mi_get_default_heap(), s);
 }
 
 // `strndup` using mi_malloc
-mi_decl_restrict char* mi_heap_strndup(mi_heap_t* heap, const char* s, size_t n) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict char* mi_heap_strndup(mi_heap_t* heap, const char* s, size_t n) mi_attr_noexcept {
   if (s == NULL) return NULL;
   const char* end = (const char*)memchr(s, 0, n);  // find end of string in the first `n` characters (returns NULL if not found)
   const size_t m = (end != NULL ? (size_t)(end - s) : n);  // `m` is the minimum of `n` or the end-of-string
@@ -734,7 +734,7 @@ mi_decl_restrict char* mi_heap_strndup(mi_heap_t* heap, const char* s, size_t n)
   return t;
 }
 
-mi_decl_restrict char* mi_strndup(const char* s, size_t n) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict char* mi_strndup(const char* s, size_t n) mi_attr_noexcept {
   return mi_heap_strndup(mi_get_default_heap(),s,n);
 }
 
@@ -745,7 +745,7 @@ mi_decl_restrict char* mi_strndup(const char* s, size_t n) mi_attr_noexcept {
 #define PATH_MAX MAX_PATH
 #endif
 #include <windows.h>
-mi_decl_restrict char* mi_heap_realpath(mi_heap_t* heap, const char* fname, char* resolved_name) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict char* mi_heap_realpath(mi_heap_t* heap, const char* fname, char* resolved_name) mi_attr_noexcept {
   // todo: use GetFullPathNameW to allow longer file names
   char buf[PATH_MAX];
   DWORD res = GetFullPathNameA(fname, PATH_MAX, (resolved_name == NULL ? buf : resolved_name), NULL);
@@ -791,7 +791,7 @@ char* mi_heap_realpath(mi_heap_t* heap, const char* fname, char* resolved_name)
 }
 #endif
 
-mi_decl_restrict char* mi_realpath(const char* fname, char* resolved_name) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict char* mi_realpath(const char* fname, char* resolved_name) mi_attr_noexcept {
   return mi_heap_realpath(mi_get_default_heap(),fname,resolved_name);
 }
 #endif
@@ -867,19 +867,19 @@ static mi_decl_noinline void* mi_try_new(size_t size, bool nothrow ) {
   return p;
 }
 
-mi_decl_restrict void* mi_new(size_t size) {
+mi_decl_nodiscard mi_decl_restrict void* mi_new(size_t size) {
   void* p = mi_malloc(size);
   if (mi_unlikely(p == NULL)) return mi_try_new(size,false);
   return p;
 }
 
-mi_decl_restrict void* mi_new_nothrow(size_t size) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict void* mi_new_nothrow(size_t size) mi_attr_noexcept {
   void* p = mi_malloc(size);
   if (mi_unlikely(p == NULL)) return mi_try_new(size, true);
   return p;
 }
 
-mi_decl_restrict void* mi_new_aligned(size_t size, size_t alignment) {
+mi_decl_nodiscard mi_decl_restrict void* mi_new_aligned(size_t size, size_t alignment) {
   void* p;
   do {
     p = mi_malloc_aligned(size, alignment);
@@ -888,7 +888,7 @@ mi_decl_restrict void* mi_new_aligned(size_t size, size_t alignment) {
   return p;
 }
 
-mi_decl_restrict void* mi_new_aligned_nothrow(size_t size, size_t alignment) mi_attr_noexcept {
+mi_decl_nodiscard mi_decl_restrict void* mi_new_aligned_nothrow(size_t size, size_t alignment) mi_attr_noexcept {
   void* p;
   do {
     p = mi_malloc_aligned(size, alignment);
@@ -897,7 +897,7 @@ mi_decl_restrict void* mi_new_aligned_nothrow(size_t size, size_t alignment) mi_
   return p;
 }
 
-mi_decl_restrict void* mi_new_n(size_t count, size_t size) {
+mi_decl_nodiscard mi_decl_restrict void* mi_new_n(size_t count, size_t size) {
   size_t total;
   if (mi_unlikely(mi_count_size_overflow(count, size, &total))) {
     mi_try_new_handler(false);  // on overflow we invoke the try_new_handler once to potentially throw std::bad_alloc
@@ -908,7 +908,7 @@ mi_decl_restrict void* mi_new_n(size_t count, size_t size) {
   }
 }
 
-void* mi_new_realloc(void* p, size_t newsize) {
+mi_decl_nodiscard void* mi_new_realloc(void* p, size_t newsize) {
   void* q;
   do {
     q = mi_realloc(p, newsize);
@@ -916,7 +916,7 @@ void* mi_new_realloc(void* p, size_t newsize) {
   return q;
 }
 
-void* mi_new_reallocn(void* p, size_t newcount, size_t size) {
+mi_decl_nodiscard void* mi_new_reallocn(void* p, size_t newcount, size_t size) {
   size_t total;
   if (mi_unlikely(mi_count_size_overflow(newcount, size, &total))) {
     mi_try_new_handler(false);  // on overflow we invoke the try_new_handler once to potentially throw std::bad_alloc
diff --git a/src/heap.c b/src/heap.c
index cf22dcc1..e14de32f 100644
--- a/src/heap.c
+++ b/src/heap.c
@@ -189,7 +189,7 @@ mi_heap_t* mi_heap_get_backing(void) {
   return bheap;
 }
 
-mi_heap_t* mi_heap_new(void) {
+mi_decl_nodiscard mi_heap_t* mi_heap_new(void) {
   mi_heap_t* bheap = mi_heap_get_backing();
   mi_heap_t* heap = mi_heap_malloc_tp(bheap, mi_heap_t);  // todo: OS allocate in secure mode?
   if (heap==NULL) return NULL;
diff --git a/test/test-api.c b/test/test-api.c
index 0302464e..5526f772 100644
--- a/test/test-api.c
+++ b/test/test-api.c
@@ -57,7 +57,9 @@ int main(void) {
   // ---------------------------------------------------
 
   CHECK_BODY("malloc-zero",{
-    void* p = mi_malloc(0); mi_free(p);
+    void* p = mi_malloc(0); 
+    result = (p != NULL);
+    mi_free(p);
   });
   CHECK_BODY("malloc-nomem1",{
     result = (mi_malloc((size_t)PTRDIFF_MAX + (size_t)1) == NULL);
@@ -174,6 +176,21 @@ int main(void) {
     result = ok;
   });
   
+  // ---------------------------------------------------
+  // Reallocation
+  // ---------------------------------------------------
+  CHECK_BODYX("realloc-null1") {
+    void* p = mi_realloc(NULL,4);
+    result = (p != NULL);
+    mi_free(p);
+  };
+
+  CHECK_BODYX("realloc-null2") {
+    void* p = mi_realloc(NULL,0);  // <https://en.cppreference.com/w/c/memory/realloc> "If ptr is NULL, the behavior is the same as calling malloc(new_size)."
+    result = (p != NULL);
+    mi_free(p);
+  };
+
   // ---------------------------------------------------
   // Heaps
   // ---------------------------------------------------
diff --git a/test/testhelper.h b/test/testhelper.h
index 46d63a00..110db557 100644
--- a/test/testhelper.h
+++ b/test/testhelper.h
@@ -15,11 +15,29 @@ terms of the MIT license. A copy of the license can be found in the file
 static int ok = 0;
 static int failed = 0;
 
+static bool check_result(bool result, const char* testname, const char* fname, long lineno) {
+  if (!(result)) {
+    failed++; 
+    fprintf(stderr,"\n  FAILED: %s: %s:%d:\n", testname, fname, lineno);
+    /* exit(1); */ 
+  } 
+  else {    
+    ok++;                               
+    fprintf(stderr, "ok.\n");
+  }
+  return true;
+}
+
+#define CHECK_BODYX(name) \
+  fprintf(stderr,"test: %s...  ", name ); \
+  for(bool done = false, result = true; !done; done = check_result(result,name,__FILE__,__LINE__))
+
+
 #define CHECK_BODY(name,body) \
  do { \
   fprintf(stderr,"test: %s...  ", name ); \
   bool result = true;                                     \
-  do { body } while(false);                                \
+  do { body } while(false);                               \
   if (!(result)) {                                        \
     failed++; \
     fprintf(stderr,                                       \
@@ -35,7 +53,7 @@ static int failed = 0;
   }                                             \
  } while (false)
 
-#define CHECK(name,expr)      CHECK_BODY(name,{ result = (expr); })
+#define CHECK(name,expr)      CHECK_BODYX(name){ result = (expr); }
 
 // Print summary of test. Return value can be directly use as a return value for main().
 static inline int print_test_summary(void)