diff --git a/reactos/lib/crt/stdlib/malloc.c b/reactos/lib/crt/stdlib/malloc.c
index 44cf4e49dec..b1227a54772 100644
--- a/reactos/lib/crt/stdlib/malloc.c
+++ b/reactos/lib/crt/stdlib/malloc.c
@@ -29,6 +29,9 @@
 /* fixme: should have this in common header */
 #define ROUND_UP(a,b) ((a + (b-1)) & ~(b-1))
 
+/* round to 16 bytes + alloc at minimum 16 bytes */
+#define ROUND_SIZE(size) (max(16, ROUND_UP(size, 16)))
+
 extern HANDLE hHeap;
 
 /*
@@ -36,7 +39,7 @@ extern HANDLE hHeap;
  */
 void* malloc(size_t _size)
 {
-   return HeapAlloc(hHeap, 0, ROUND_UP(_size, 16));
+   return HeapAlloc(hHeap, 0, ROUND_SIZE(_size));
 }
 
 /*
@@ -52,7 +55,7 @@ void free(void* _ptr)
  */
 void* calloc(size_t _nmemb, size_t _size)
 {
-   return HeapAlloc(hHeap, HEAP_ZERO_MEMORY, ROUND_UP(_nmemb*_size, 16) );
+   return HeapAlloc(hHeap, HEAP_ZERO_MEMORY, ROUND_SIZE(_nmemb*_size) );
 }
 
 /*
@@ -60,9 +63,10 @@ void* calloc(size_t _nmemb, size_t _size)
  */
 void* realloc(void* _ptr, size_t _size)
 {
-   if (!_ptr)
-      return HeapAlloc(hHeap, 0, ROUND_UP(_size, 16));
-   return HeapReAlloc(hHeap, 0, _ptr, ROUND_UP(_size, 16));
+   if (!_ptr) return malloc(_size);
+   if (_size) return HeapReAlloc(hHeap, 0, _ptr, ROUND_SIZE(_size));
+   free(_ptr);
+   return NULL;
 }
 
 /*
@@ -70,7 +74,7 @@ void* realloc(void* _ptr, size_t _size)
  */
 void* _expand(void* _ptr, size_t _size)
 {
-   return HeapReAlloc(hHeap, HEAP_REALLOC_IN_PLACE_ONLY, _ptr, ROUND_UP(_size, 16));
+   return HeapReAlloc(hHeap, HEAP_REALLOC_IN_PLACE_ONLY, _ptr, ROUND_SIZE(_size));
 }
 
 /*