diff --git a/include/mimalloc-track.h b/include/mimalloc-track.h
index 8326c620..b2404f8d 100644
--- a/include/mimalloc-track.h
+++ b/include/mimalloc-track.h
@@ -24,8 +24,9 @@ uses the block start pointer and original size (corresponding to the `mi_track_m
 
 #if MI_VALGRIND
 
-#define MI_TRACK_ENABLED 1
-#define MI_TRACK_TOOL    "valgrind"
+#define MI_TRACK_ENABLED      1
+#define MI_TRACK_HEAP_DESTROY 1           // track free of individual blocks on heap_destroy
+#define MI_TRACK_TOOL         "valgrind"
 
 #include <valgrind/valgrind.h>
 #include <valgrind/memcheck.h>
@@ -39,8 +40,9 @@ uses the block start pointer and original size (corresponding to the `mi_track_m
 
 #elif MI_ASAN
 
-#define MI_TRACK_ENABLED 1
-#define MI_TRACK_TOOL    "asan"
+#define MI_TRACK_ENABLED      1
+#define MI_TRACK_HEAP_DESTROY 0
+#define MI_TRACK_TOOL         "asan"
 
 #include <sanitizer/asan_interface.h>
 
@@ -52,8 +54,9 @@ uses the block start pointer and original size (corresponding to the `mi_track_m
 
 #else
 
-#define MI_TRACK_ENABLED 0
-#define MI_TRACK_TOOL    "none"
+#define MI_TRACK_ENABLED      0
+#define MI_TRACK_HEAP_DESTROY 0 
+#define MI_TRACK_TOOL         "none"
 
 #define mi_track_malloc_size(p,reqsize,size,zero)
 #define mi_track_free_size(p,_size)
diff --git a/src/alloc-aligned.c b/src/alloc-aligned.c
index 19047f44..1e27a306 100644
--- a/src/alloc-aligned.c
+++ b/src/alloc-aligned.c
@@ -74,17 +74,17 @@ static mi_decl_noinline void* mi_heap_malloc_zero_aligned_at_fallback(mi_heap_t*
   mi_assert_internal(mi_usable_size(p) == mi_usable_size(aligned_p)+adjust);
     
   // now zero the block if needed
-  if (zero && alignment > MI_ALIGNMENT_MAX) {
-    const ptrdiff_t diff = (uint8_t*)aligned_p - (uint8_t*)p;
-    const ptrdiff_t zsize = mi_page_usable_block_size(_mi_ptr_page(p)) - diff - MI_PADDING_SIZE;
-    if (zsize > 0) { _mi_memzero(aligned_p, zsize); }
+  if (alignment > MI_ALIGNMENT_MAX) {
+    // for the tracker, on huge aligned allocations only from the start of the large block is defined
+    mi_track_mem_undefined(aligned_p, size);
+    if (zero) {
+      _mi_memzero(aligned_p, mi_usable_size(aligned_p));
+    }
   }
 
-  #if MI_TRACK_ENABLED
   if (p != aligned_p) {
     mi_track_align(p,aligned_p,adjust,mi_usable_size(aligned_p));
-  }
-  #endif
+  }  
   return aligned_p;
 }
 
diff --git a/src/heap.c b/src/heap.c
index ac2d042b..dfeb172d 100644
--- a/src/heap.c
+++ b/src/heap.c
@@ -8,6 +8,7 @@ terms of the MIT license. A copy of the license can be found in the file
 #include "mimalloc.h"
 #include "mimalloc-internal.h"
 #include "mimalloc-atomic.h"
+#include "mimalloc-track.h"
 
 #include <string.h>  // memset, memcpy
 
@@ -330,6 +331,12 @@ void _mi_heap_destroy_pages(mi_heap_t* heap) {
   mi_heap_reset_pages(heap);
 }
 
+static bool mi_cdecl mi_heap_track_block_free(const mi_heap_t* heap, const mi_heap_area_t* area, void* block, size_t block_size, void* arg) {
+  MI_UNUSED(heap); MI_UNUSED(area);  MI_UNUSED(arg); MI_UNUSED(block_size);
+  mi_track_free_size(block,mi_usable_size(block));
+  return true;
+}
+
 void mi_heap_destroy(mi_heap_t* heap) {
   mi_assert(heap != NULL);
   mi_assert(mi_heap_is_initialized(heap));
@@ -341,6 +348,10 @@ void mi_heap_destroy(mi_heap_t* heap) {
     mi_heap_delete(heap);
   }
   else {
+    // track all blocks as freed
+    #if MI_TRACK_HEAP_DESTROY
+    mi_heap_visit_blocks(heap, true, mi_heap_track_block_free, NULL);
+    #endif
     // free all pages
     _mi_heap_destroy_pages(heap);
     mi_heap_free(heap);
diff --git a/test/test-wrong.c b/test/test-wrong.c
index 17d253b6..aaaf60b9 100644
--- a/test/test-wrong.c
+++ b/test/test-wrong.c
@@ -5,7 +5,10 @@ terms of the MIT license. A copy of the license can be found in the file
 "LICENSE" at the root of this distribution.
 -----------------------------------------------------------------------------*/
 
-/* test file for valgrind support.
+/* test file for valgrind/asan support.
+
+   VALGRIND:
+   ----------
    Compile in an "out/debug" folder:
 
    > cd out/debug
@@ -19,6 +22,25 @@ terms of the MIT license. A copy of the license can be found in the file
    and test as:
 
    > valgrind ./test-wrong
+
+   
+   ASAN
+   ----------
+   Compile in an "out/debug" folder:
+
+   > cd out/debug
+   > cmake ../.. -DMI_ASAN=1
+   > make -j8
+
+   and then compile this file as:
+
+   > clang -g -o test-wrong -I../../include ../../test/test-wrong.c libmimalloc-asan-debug.a -lpthread -fsanitize=address -fsanitize-recover=address
+
+   and test as:
+
+   > ASAN_OPTIONS=verbosity=1:halt_on_error=0 ./test-wrong
+
+
 */
 #include <stdio.h>
 #include <stdlib.h>