diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2e9169b7..84668eb3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,7 +67,7 @@ endif()
 
 if(MI_SECURE MATCHES "ON")
   message(STATUS "Set secure build (MI_SECURE=ON)")
-  list(APPEND mi_defines MI_SECURE=2)
+  list(APPEND mi_defines MI_SECURE=3)
 endif()
 
 if(MI_SEE_ASM MATCHES "ON")
diff --git a/ide/vs2019/mimalloc.vcxproj b/ide/vs2019/mimalloc.vcxproj
index f10497a2..2af40f16 100644
--- a/ide/vs2019/mimalloc.vcxproj
+++ b/ide/vs2019/mimalloc.vcxproj
@@ -116,7 +116,7 @@
       <SDLCheck>true</SDLCheck>
       <ConformanceMode>true</ConformanceMode>
       <AdditionalIncludeDirectories>../../include</AdditionalIncludeDirectories>
-      <PreprocessorDefinitions>MI_DEBUG=3;%(PreprocessorDefinitions);</PreprocessorDefinitions>
+      <PreprocessorDefinitions>MI_DEBUG=1;%(PreprocessorDefinitions);</PreprocessorDefinitions>
       <CompileAs>CompileAsCpp</CompileAs>
       <SupportJustMyCode>false</SupportJustMyCode>
       <LanguageStandard>stdcpp17</LanguageStandard>
diff --git a/include/mimalloc-internal.h b/include/mimalloc-internal.h
index b1c468bd..8d6cc291 100644
--- a/include/mimalloc-internal.h
+++ b/include/mimalloc-internal.h
@@ -20,6 +20,18 @@ terms of the MIT license. A copy of the license can be found in the file
 #define mi_trace_message(...)
 #endif
 
+#if defined(_MSC_VER)
+#define mi_decl_noinline   __declspec(noinline)
+#define mi_attr_noreturn 
+#elif defined(__GNUC__) || defined(__clang__)
+#define mi_decl_noinline   __attribute__((noinline))
+#define mi_attr_noreturn   __attribute__((noreturn))
+#else
+#define mi_decl_noinline
+#define mi_attr_noreturn   
+#endif
+
+
 // "options.c"
 void       _mi_fputs(mi_output_fun* out, const char* prefix, const char* message);
 void       _mi_fprintf(mi_output_fun* out, const char* fmt, ...);
@@ -28,12 +40,12 @@ void       _mi_warning_message(const char* fmt, ...);
 void       _mi_verbose_message(const char* fmt, ...);
 void       _mi_trace_message(const char* fmt, ...);
 void       _mi_options_init(void);
+void       _mi_fatal_error(const char* fmt, ...) mi_attr_noreturn;
 
 // "init.c"
 extern mi_stats_t       _mi_stats_main;
 extern const mi_page_t  _mi_page_empty;
 bool       _mi_is_main_thread(void);
-uintptr_t  _mi_ptr_cookie(const void* p);
 uintptr_t  _mi_random_shuffle(uintptr_t x);
 uintptr_t  _mi_random_init(uintptr_t seed /* can be zero */);
 bool       _mi_preloading();  // true while the C runtime is not ready
@@ -135,13 +147,6 @@ bool        _mi_page_is_valid(mi_page_t* page);
 #define __has_builtin(x)  0
 #endif
 
-#if defined(_MSC_VER)
-#define mi_decl_noinline   __declspec(noinline)
-#elif defined(__GNUC__) || defined(__clang__)
-#define mi_decl_noinline   __attribute__((noinline))
-#else
-#define mi_decl_noinline
-#endif
 
 
 /* -----------------------------------------------------------
@@ -254,6 +259,10 @@ static inline bool mi_heap_is_initialized(mi_heap_t* heap) {
   return (heap != &_mi_heap_empty);
 }
 
+static inline uintptr_t _mi_ptr_cookie(const void* p) {
+  return ((uintptr_t)p ^ _mi_heap_main.cookie);
+}
+
 /* -----------------------------------------------------------
   Pages
 ----------------------------------------------------------- */
@@ -401,8 +410,12 @@ static inline void mi_page_set_has_aligned(mi_page_t* page, bool has_aligned) {
 // Encoding/Decoding the free list next pointers
 // -------------------------------------------------------------------
 
-static inline mi_block_t* mi_block_nextx( uintptr_t cookie, mi_block_t* block ) {
-  #if MI_SECURE
+static inline bool mi_is_in_same_segment(const void* p, const void* q) {
+  return (_mi_ptr_segment(p) == _mi_ptr_segment(q));
+}
+
+static inline mi_block_t* mi_block_nextx( uintptr_t cookie, const mi_block_t* block ) {
+  #if MI_SECURE 
   return (mi_block_t*)(block->next ^ cookie);
   #else
   UNUSED(cookie);
@@ -410,7 +423,7 @@ static inline mi_block_t* mi_block_nextx( uintptr_t cookie, mi_block_t* block )
   #endif
 }
 
-static inline void mi_block_set_nextx(uintptr_t cookie, mi_block_t* block, mi_block_t* next) {
+static inline void mi_block_set_nextx(uintptr_t cookie, mi_block_t* block, const mi_block_t* next) {  
   #if MI_SECURE
   block->next = (mi_encoded_t)next ^ cookie;
   #else
@@ -419,16 +432,25 @@ static inline void mi_block_set_nextx(uintptr_t cookie, mi_block_t* block, mi_bl
   #endif
 }
 
-static inline mi_block_t* mi_block_next(mi_page_t* page, mi_block_t* block) {
+static inline mi_block_t* mi_block_next(const mi_page_t* page, const mi_block_t* block) {
   #if MI_SECURE
-  return mi_block_nextx(page->cookie,block);
+  mi_block_t* next = mi_block_nextx(page->cookie,block);
+    #if MI_SECURE >= 4
+    // check if next is at least in our segment range
+    // TODO: it is better to check if it is actually inside our page but that is more expensive 
+    // to calculate. Perhaps with a relative free list this becomes feasible?
+    if (next!=NULL && !mi_is_in_same_segment(block, next)) {
+      _mi_fatal_error("corrupted free list entry at %p: %zx\n", block, (uintptr_t)next);
+    }
+    #endif
+  return next;
   #else
   UNUSED(page);
   return mi_block_nextx(0, block);
   #endif
 }
 
-static inline void mi_block_set_next(mi_page_t* page, mi_block_t* block, mi_block_t* next) {
+static inline void mi_block_set_next(const mi_page_t* page, mi_block_t* block, const mi_block_t* next) {
   #if MI_SECURE
   mi_block_set_nextx(page->cookie,block,next);
   #else
diff --git a/include/mimalloc-types.h b/include/mimalloc-types.h
index 422fc24d..e49893bb 100644
--- a/include/mimalloc-types.h
+++ b/include/mimalloc-types.h
@@ -22,8 +22,11 @@ terms of the MIT license. A copy of the license can be found in the file
 // Define MI_STAT as 1 to maintain statistics; set it to 2 to have detailed statistics (but costs some performance).
 // #define MI_STAT 1
 
-// Define MI_SECURE as 1 to encode free lists
-// #define MI_SECURE 1
+// Define MI_SECURE to enable security mitigations
+// #define MI_SECURE 1  // guard page around metadata
+// #define MI_SECURE 2  // guard page around each mimalloc page
+// #define MI_SECURE 3  // encode free lists
+// #define MI_SECURE 4  // all security enabled (checks for double free, corrupted free list and invalid pointer free)
 
 #if !defined(MI_SECURE)
 #define MI_SECURE 0
diff --git a/src/alloc.c b/src/alloc.c
index 230e5b39..4f5e5b4f 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -124,10 +124,54 @@ mi_decl_allocator void* mi_zalloc(size_t size) mi_attr_noexcept {
 }
 
 
+// ------------------------------------------------------
+// Check for double free in secure mode
+// ------------------------------------------------------
+
+#if MI_SECURE>=4
+static bool mi_list_contains(const mi_page_t* page, const mi_block_t* list, const mi_block_t* elem) {
+  while (list != NULL) {
+    if (elem==list) return true;
+    list = mi_block_next(page, list);
+  }
+  return false;
+}
+
+static mi_decl_noinline bool mi_check_double_freex(const mi_page_t* page, const mi_block_t* block, const mi_block_t* n) {
+  size_t psize;
+  uint8_t* pstart = _mi_page_start(_mi_page_segment(page), page, &psize);
+  if (n == NULL || ((uint8_t*)n >= pstart && (uint8_t*)n < (pstart + psize))) {
+    // Suspicious: the decoded value is in the same page (or NULL).
+    // Walk the free lists to see if it is already freed
+    if (mi_list_contains(page, page->free, block) ||
+      mi_list_contains(page, page->local_free, block) ||
+      mi_list_contains(page, (const mi_block_t*)mi_atomic_read_ptr_relaxed(mi_atomic_cast(void*,&page->thread_free)), block)) 
+    {
+      _mi_fatal_error("double free detected of block %p with size %zu\n", block, page->block_size);
+      return true;
+    }
+  }
+  return false;
+}
+
+static inline bool mi_check_double_free(const mi_page_t* page, const mi_block_t* block) {
+  mi_block_t* n = (mi_block_t*)(block->next ^ page->cookie);
+  if (((uintptr_t)n & (MI_INTPTR_SIZE-1))==0 &&       // quick check 
+      (n==NULL || mi_is_in_same_segment(block, n))) 
+  { 
+    // Suspicous: decoded value in block is in the same segment (or NULL) -- maybe a double free?
+    return mi_check_double_freex(page, block, n);
+  }  
+  return false;
+}
+#endif
+
+
 // ------------------------------------------------------
 // Free
 // ------------------------------------------------------
 
+
 // multi-threaded free
 static mi_decl_noinline void _mi_free_block_mt(mi_page_t* page, mi_block_t* block)
 {
@@ -251,14 +295,16 @@ void mi_free(void* p) mi_attr_noexcept
 
 #if (MI_DEBUG>0)
   if (mi_unlikely(!mi_is_in_heap_region(p))) {
-    _mi_warning_message("possibly trying to mi_free a pointer that does not point to a valid heap region: 0x%p\n"
+    _mi_warning_message("possibly trying to free a pointer that does not point to a valid heap region: 0x%p\n"
       "(this may still be a valid very large allocation (over 64MiB))\n", p);
     if (mi_likely(_mi_ptr_cookie(segment) == segment->cookie)) {
       _mi_warning_message("(yes, the previous pointer 0x%p was valid after all)\n", p);
     }
   }
+#endif
+#if (MI_DEBUG>0 || MI_SECURE>=4)
   if (mi_unlikely(_mi_ptr_cookie(segment) != segment->cookie)) {
-    _mi_error_message("trying to mi_free a pointer that does not point to a valid heap space: %p\n", p);
+    _mi_error_message("trying to free a pointer that does not point to a valid heap space: %p\n", p);
     return;
   }
 #endif
@@ -278,6 +324,9 @@ void mi_free(void* p) mi_attr_noexcept
   if (mi_likely(tid == segment->thread_id && page->flags.full_aligned == 0)) {  // the thread id matches and it is not a full page, nor has aligned blocks
     // local, and not full or aligned
     mi_block_t* block = (mi_block_t*)p;
+    #if MI_SECURE>=4 
+    if (mi_check_double_free(page,block)) return;
+    #endif
     mi_block_set_next(page, block, page->local_free);
     page->local_free = block;
     page->used--;
diff --git a/src/init.c b/src/init.c
index 2c7dc581..4da6c5ae 100644
--- a/src/init.c
+++ b/src/init.c
@@ -208,10 +208,6 @@ uintptr_t _mi_random_init(uintptr_t seed /* can be zero */) {
   return x;
 }
 
-uintptr_t _mi_ptr_cookie(const void* p) {
-  return ((uintptr_t)p ^ _mi_heap_main.cookie);
-}
-
 /* -----------------------------------------------------------
   Initialization and freeing of the thread local heaps
 ----------------------------------------------------------- */
diff --git a/src/memory.c b/src/memory.c
index f9c53782..0f9f5dec 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -139,7 +139,7 @@ Commit from a region
 // Returns `false` on an error (OOM); `true` otherwise. `p` and `id` are only written
 // if the blocks were successfully claimed so ensure they are initialized to NULL/SIZE_MAX before the call.
 // (not being able to claim is not considered an error so check for `p != NULL` afterwards).
-static bool mi_region_commit_blocks(mem_region_t* region, size_t idx, size_t bitidx, size_t blocks, 
+static bool mi_region_commit_blocks(mem_region_t* region, size_t idx, size_t bitidx, size_t blocks,
                                     size_t size, bool* commit, bool* allow_large, bool* is_zero, void** p, size_t* id, mi_os_tld_t* tld)
 {
   size_t mask = mi_region_block_mask(blocks,bitidx);
@@ -149,7 +149,7 @@ static bool mi_region_commit_blocks(mem_region_t* region, size_t idx, size_t bit
 
   // ensure the region is reserved
   mi_region_info_t info = mi_atomic_read(&region->info);
-  if (info == 0) 
+  if (info == 0)
   {
     bool region_commit = mi_option_is_enabled(mi_option_eager_region_commit);
     bool region_large  = *allow_large;
@@ -202,7 +202,7 @@ static bool mi_region_commit_blocks(mem_region_t* region, size_t idx, size_t bit
   // Commit the blocks to memory
   bool region_is_committed = false;
   bool region_is_large = false;
-  void* start = mi_region_info_read(info,&region_is_large,&region_is_committed);  
+  void* start = mi_region_info_read(info,&region_is_large,&region_is_committed);
   mi_assert_internal(!(region_is_large && !*allow_large));
   mi_assert_internal(start!=NULL);
 
@@ -215,7 +215,7 @@ static bool mi_region_commit_blocks(mem_region_t* region, size_t idx, size_t bit
 
   void* blocks_start = (uint8_t*)start + (bitidx * MI_SEGMENT_SIZE);
   if (*commit && !region_is_committed) {
-    // ensure commit 
+    // ensure commit
     bool commit_zero = false;
     _mi_os_commit(blocks_start, mi_good_commit_size(size), &commit_zero, tld->stats);  // only commit needed size (unless using large OS pages)
     if (commit_zero) *is_zero = true;
@@ -225,7 +225,7 @@ static bool mi_region_commit_blocks(mem_region_t* region, size_t idx, size_t bit
     *commit = true;
   }
 
-  // and return the allocation  
+  // and return the allocation
   mi_assert_internal(blocks_start != NULL);
   *allow_large = region_is_large;
   *p  = blocks_start;
@@ -271,7 +271,7 @@ static inline size_t mi_bsr(uintptr_t x) {
 // Returns `false` on an error (OOM); `true` otherwise. `p` and `id` are only written
 // if the blocks were successfully claimed so ensure they are initialized to NULL/SIZE_MAX before the call.
 // (not being able to claim is not considered an error so check for `p != NULL` afterwards).
-static bool mi_region_alloc_blocks(mem_region_t* region, size_t idx, size_t blocks, size_t size, 
+static bool mi_region_alloc_blocks(mem_region_t* region, size_t idx, size_t blocks, size_t size,
                                    bool* commit, bool* allow_large, bool* is_zero, void** p, size_t* id, mi_os_tld_t* tld)
 {
   mi_assert_internal(p != NULL && id != NULL);
@@ -303,7 +303,7 @@ static bool mi_region_alloc_blocks(mem_region_t* region, size_t idx, size_t bloc
       else {
         // success, we claimed the bits
         // now commit the block memory -- this can still fail
-        return mi_region_commit_blocks(region, idx, bitidx, blocks, 
+        return mi_region_commit_blocks(region, idx, bitidx, blocks,
                                        size, commit, allow_large, is_zero, p, id, tld);
       }
     }
@@ -327,20 +327,20 @@ static bool mi_region_alloc_blocks(mem_region_t* region, size_t idx, size_t bloc
 // Returns `false` on an error (OOM); `true` otherwise. `p` and `id` are only written
 // if the blocks were successfully claimed so ensure they are initialized to NULL/0 before the call.
 // (not being able to claim is not considered an error so check for `p != NULL` afterwards).
-static bool mi_region_try_alloc_blocks(size_t idx, size_t blocks, size_t size, 
-                                       bool* commit, bool* allow_large, bool* is_zero, 
+static bool mi_region_try_alloc_blocks(size_t idx, size_t blocks, size_t size,
+                                       bool* commit, bool* allow_large, bool* is_zero,
                                        void** p, size_t* id, mi_os_tld_t* tld)
 {
   // check if there are available blocks in the region..
   mi_assert_internal(idx < MI_REGION_MAX);
   mem_region_t* region = &regions[idx];
   uintptr_t m = mi_atomic_read_relaxed(&region->map);
-  if (m != MI_REGION_MAP_FULL) {  // some bits are zero    
+  if (m != MI_REGION_MAP_FULL) {  // some bits are zero
     bool ok = (*commit || *allow_large); // committing or allow-large is always ok
     if (!ok) {
-      // otherwise skip incompatible regions if possible. 
+      // otherwise skip incompatible regions if possible.
       // this is not guaranteed due to multiple threads allocating at the same time but
-      // that's ok. In secure mode, large is never allowed for any thread, so that works out; 
+      // that's ok. In secure mode, large is never allowed for any thread, so that works out;
       // otherwise we might just not be able to reset/decommit individual pages sometimes.
       mi_region_info_t info = mi_atomic_read_relaxed(&region->info);
       bool is_large;
@@ -361,7 +361,7 @@ static bool mi_region_try_alloc_blocks(size_t idx, size_t blocks, size_t size,
 
 // Allocate `size` memory aligned at `alignment`. Return non NULL on success, with a given memory `id`.
 // (`id` is abstract, but `id = idx*MI_REGION_MAP_BITS + bitidx`)
-void* _mi_mem_alloc_aligned(size_t size, size_t alignment, bool* commit, bool* large, bool* is_zero, 
+void* _mi_mem_alloc_aligned(size_t size, size_t alignment, bool* commit, bool* large, bool* is_zero,
                             size_t* id, mi_os_tld_t* tld)
 {
   mi_assert_internal(id != NULL && tld != NULL);
@@ -369,7 +369,7 @@ void* _mi_mem_alloc_aligned(size_t size, size_t alignment, bool* commit, bool* l
   *id = SIZE_MAX;
   *is_zero = false;
   bool default_large = false;
-  if (large==NULL) large = &default_large;  // ensure `large != NULL`  
+  if (large==NULL) large = &default_large;  // ensure `large != NULL`
 
   // use direct OS allocation for huge blocks or alignment (with `id = SIZE_MAX`)
   if (size > MI_REGION_MAX_ALLOC_SIZE || alignment > MI_SEGMENT_ALIGN) {
@@ -465,7 +465,7 @@ void _mi_mem_free(void* p, size_t size, size_t id, mi_stats_t* stats) {
         // _mi_os_decommit(p,size,stats); // if !is_eager_committed (and clear dirty bits)
       }
       // else { _mi_os_reset(p,size,stats); }
-    }    
+    }
     if (!is_eager_committed) {
       // adjust commit statistics as we commit again when re-using the same slot
       _mi_stat_decrease(&stats->committed, mi_good_commit_size(size));
diff --git a/src/options.c b/src/options.c
index 81c8ba2c..9b0c87a5 100644
--- a/src/options.c
+++ b/src/options.c
@@ -285,6 +285,14 @@ void _mi_assert_fail(const char* assertion, const char* fname, unsigned line, co
 }
 #endif
 
+mi_attr_noreturn void _mi_fatal_error(const char* fmt, ...) {
+  va_list args;
+  va_start(args, fmt);
+  mi_vfprintf(NULL, "mimalloc: fatal: ", fmt, args);
+  va_end(args);
+  exit(99);
+}
+
 // --------------------------------------------------------
 // Initialize options by checking the environment
 // --------------------------------------------------------
diff --git a/src/os.c b/src/os.c
index d7d9c733..1c6093d7 100644
--- a/src/os.c
+++ b/src/os.c
@@ -95,7 +95,7 @@ typedef NTSTATUS (__stdcall *PNtAllocateVirtualMemoryEx)(HANDLE, PVOID*, SIZE_T*
 static PVirtualAlloc2 pVirtualAlloc2 = NULL;
 static PNtAllocateVirtualMemoryEx pNtAllocateVirtualMemoryEx = NULL;
 
-static bool mi_win_enable_large_os_pages() 
+static bool mi_win_enable_large_os_pages()
 {
   if (large_os_page_size > 0) return true;
 
@@ -149,7 +149,7 @@ void _mi_os_init(void) {
   if (hDll != NULL) {    
     pNtAllocateVirtualMemoryEx = (PNtAllocateVirtualMemoryEx)(void (*)(void))GetProcAddress(hDll, "NtAllocateVirtualMemoryEx");
     FreeLibrary(hDll);
-  }  
+  }
   if (mi_option_is_enabled(mi_option_large_os_pages) || mi_option_is_enabled(mi_option_reserve_huge_os_pages)) {
     mi_win_enable_large_os_pages();
   }
@@ -189,7 +189,7 @@ static bool mi_os_mem_free(void* addr, size_t size, bool was_committed, mi_stats
 #else
   err = (munmap(addr, size) == -1);
 #endif
-  if (was_committed) _mi_stat_decrease(&stats->committed, size); 
+  if (was_committed) _mi_stat_decrease(&stats->committed, size);
   _mi_stat_decrease(&stats->reserved, size);
   if (err) {
 #pragma warning(suppress:4996)
@@ -233,14 +233,14 @@ static void* mi_win_virtual_allocx(void* addr, size_t size, size_t try_alignment
     }
   }
 #endif
-#if (MI_INTPTR_SIZE >= 8) 
+#if (MI_INTPTR_SIZE >= 8)
   // on 64-bit systems, try to use the virtual address area after 4TiB for 4MiB aligned allocations
   void* hint;
   if (addr == NULL && (hint = mi_os_get_aligned_hint(try_alignment,size)) != NULL) {
     return VirtualAlloc(hint, size, flags, PAGE_READWRITE);
   }
 #endif
-#if defined(MEM_EXTENDED_PARAMETER_TYPE_BITS)  
+#if defined(MEM_EXTENDED_PARAMETER_TYPE_BITS)
   // on modern Windows try use VirtualAlloc2 for aligned allocation
   if (try_alignment > 0 && (try_alignment % _mi_os_page_size()) == 0 && pVirtualAlloc2 != NULL) {
     MEM_ADDRESS_REQUIREMENTS reqs = { 0 };
@@ -258,7 +258,7 @@ static void* mi_win_virtual_alloc(void* addr, size_t size, size_t try_alignment,
   mi_assert_internal(!(large_only && !allow_large));
   static volatile _Atomic(uintptr_t) large_page_try_ok; // = 0;
   void* p = NULL;
-  if ((large_only || use_large_os_page(size, try_alignment)) 
+  if ((large_only || use_large_os_page(size, try_alignment))
       && allow_large && (flags&MEM_COMMIT)!=0 && (flags&MEM_RESERVE)!=0) {
     uintptr_t try_ok = mi_atomic_read(&large_page_try_ok);
     if (!large_only && try_ok > 0) {
@@ -282,7 +282,7 @@ static void* mi_win_virtual_alloc(void* addr, size_t size, size_t try_alignment,
     p = mi_win_virtual_allocx(addr, size, try_alignment, flags);
   }
   if (p == NULL) {
-    _mi_warning_message("unable to alloc mem error: err: %i size: 0x%x \n", GetLastError(), size);
+    _mi_warning_message("unable to allocate memory: error code: %i, addr: %p, size: 0x%x, large only: %d, allow_large: %d\n", GetLastError(), addr, size, large_only, allow_large);
   }
   return p;
 }
@@ -398,7 +398,7 @@ static void* mi_unix_mmap(void* addr, size_t size, size_t try_alignment, int pro
   }
   if (p == NULL) {
     *is_large = false;
-    p = mi_unix_mmapx(addr, size, try_alignment, protect_flags, flags, fd);    
+    p = mi_unix_mmapx(addr, size, try_alignment, protect_flags, flags, fd);
     #if defined(MADV_HUGEPAGE)
     // Many Linux systems don't allow MAP_HUGETLB but they support instead
     // transparent huge pages (TPH). It is not required to call `madvise` with MADV_HUGE
@@ -417,7 +417,7 @@ static void* mi_unix_mmap(void* addr, size_t size, size_t try_alignment, int pro
 }
 #endif
 
-// On 64-bit systems, we can do efficient aligned allocation by using 
+// On 64-bit systems, we can do efficient aligned allocation by using
 // the 4TiB to 30TiB area to allocate them.
 #if (MI_INTPTR_SIZE >= 8) && (defined(_WIN32) || (defined(MI_OS_USE_MMAP) && !defined(MAP_ALIGNED)))
 static volatile _Atomic(intptr_t) aligned_base;
@@ -824,7 +824,7 @@ typedef struct mi_huge_info_s {
 static mi_huge_info_t os_huge_reserved = { NULL, 0, ATOMIC_VAR_INIT(0) };
 
 bool _mi_os_is_huge_reserved(void* p) {
-  return (mi_atomic_read_ptr(&os_huge_reserved.start) != NULL && 
+  return (mi_atomic_read_ptr(&os_huge_reserved.start) != NULL &&
           p >= mi_atomic_read_ptr(&os_huge_reserved.start) &&
           (uint8_t*)p < (uint8_t*)mi_atomic_read_ptr(&os_huge_reserved.start) + mi_atomic_read(&os_huge_reserved.reserved));
 }
@@ -833,14 +833,14 @@ void* _mi_os_try_alloc_from_huge_reserved(size_t size, size_t try_alignment)
 {
   // only allow large aligned allocations (e.g. regions)
   if (size < MI_SEGMENT_SIZE || (size % MI_SEGMENT_SIZE) != 0) return NULL;
-  if (try_alignment > MI_SEGMENT_SIZE) return NULL;  
+  if (try_alignment > MI_SEGMENT_SIZE) return NULL;
   if (mi_atomic_read_ptr(&os_huge_reserved.start)==NULL) return NULL;
   if (mi_atomic_read(&os_huge_reserved.used) >= mi_atomic_read(&os_huge_reserved.reserved)) return NULL; // already full
 
   // always aligned
   mi_assert_internal(mi_atomic_read(&os_huge_reserved.used) % MI_SEGMENT_SIZE == 0 );
   mi_assert_internal( (uintptr_t)mi_atomic_read_ptr(&os_huge_reserved.start) % MI_SEGMENT_SIZE == 0 );
-  
+
   // try to reserve space
   size_t base = mi_atomic_addu( &os_huge_reserved.used, size );
   if ((base + size) > os_huge_reserved.reserved) {
@@ -871,13 +871,13 @@ static void mi_os_free_huge_reserved() {
 int mi_reserve_huge_os_pages(size_t pages, double max_secs, size_t* pages_reserved) mi_attr_noexcept {
   UNUSED(pages); UNUSED(max_secs);
   if (pages_reserved != NULL) *pages_reserved = 0;
-  return ENOMEM; 
+  return ENOMEM;
 }
 #else
 int mi_reserve_huge_os_pages( size_t pages, double max_secs, size_t* pages_reserved ) mi_attr_noexcept
 {
   if (pages_reserved != NULL) *pages_reserved = 0;
-  if (max_secs==0) return ETIMEDOUT; // timeout 
+  if (max_secs==0) return ETIMEDOUT; // timeout
   if (pages==0) return 0;            // ok
   if (!mi_atomic_cas_ptr_strong(&os_huge_reserved.start,(void*)1,NULL)) return ETIMEDOUT; // already reserved
 
@@ -894,22 +894,22 @@ int mi_reserve_huge_os_pages( size_t pages, double max_secs, size_t* pages_reser
   uint8_t* addr = start;  // current top of the allocations
   for (size_t page = 0; page < pages; page++, addr += MI_HUGE_OS_PAGE_SIZE ) {
     // allocate a page
-    void* p = NULL; 
+    void* p = NULL;
     bool is_large = true;
     #ifdef _WIN32
     if (page==0) { mi_win_enable_large_os_pages(); }
     p = mi_win_virtual_alloc(addr, MI_HUGE_OS_PAGE_SIZE, 0, MEM_LARGE_PAGES | MEM_COMMIT | MEM_RESERVE, true, true, &is_large);
     #elif defined(MI_OS_USE_MMAP)
     p = mi_unix_mmap(addr, MI_HUGE_OS_PAGE_SIZE, 0, PROT_READ | PROT_WRITE, true, true, &is_large);
-    #else 
+    #else
     // always fail
-    #endif  
-    
+    #endif
+
     // Did we succeed at a contiguous address?
     if (p != addr) {
-      // no success, issue a warning and return with an error 
+      // no success, issue a warning and return with an error
       if (p != NULL) {
-        _mi_warning_message("could not allocate contiguous huge page %zu at 0x%p\n", page, addr); 
+        _mi_warning_message("could not allocate contiguous huge page %zu at 0x%p\n", page, addr);
         _mi_os_free(p, MI_HUGE_OS_PAGE_SIZE, &_mi_stats_main );
       }
       else {
@@ -920,7 +920,7 @@ int mi_reserve_huge_os_pages( size_t pages, double max_secs, size_t* pages_reser
         #endif
         _mi_warning_message("could not allocate huge page %zu at 0x%p, error: %i\n", page, addr, err);
       }
-      return ENOMEM;  
+      return ENOMEM;
     }
     // success, record it
     if (page==0) {
@@ -930,20 +930,19 @@ int mi_reserve_huge_os_pages( size_t pages, double max_secs, size_t* pages_reser
     else {
       mi_atomic_addu(&os_huge_reserved.reserved,MI_HUGE_OS_PAGE_SIZE);
     }
-    _mi_stat_increase(&_mi_stats_main.committed, MI_HUGE_OS_PAGE_SIZE); 
+    _mi_stat_increase(&_mi_stats_main.committed, MI_HUGE_OS_PAGE_SIZE);
     _mi_stat_increase(&_mi_stats_main.reserved, MI_HUGE_OS_PAGE_SIZE);
     if (pages_reserved != NULL) { *pages_reserved = page + 1; }
 
     // check for timeout
     double elapsed = _mi_clock_end(start_t);
-    if (elapsed > max_secs) return ETIMEDOUT; 
+    if (elapsed > max_secs) return ETIMEDOUT;
     if (page >= 1) {
       double estimate = ((elapsed / (double)(page+1)) * (double)pages);
       if (estimate > 1.5*max_secs) return ETIMEDOUT; // seems like we are going to timeout
     }
-  }  
+  }
   _mi_verbose_message("reserved %zu huge pages\n", pages);
   return 0;
 }
 #endif
-
diff --git a/test/main-override-static.c b/test/main-override-static.c
index fce319fb..de6d4553 100644
--- a/test/main-override-static.c
+++ b/test/main-override-static.c
@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <assert.h>
 #include <string.h>
+#include <stdint.h>
 
 #include <mimalloc.h>
 #include <mimalloc-override.h>  // redefines malloc etc.
@@ -172,6 +173,7 @@ void mi_bins() {
 int main() {
   mi_version();
   mi_bins();
+
   void* p1 = malloc(78);
   void* p2 = malloc(24);
   free(p1);
@@ -194,3 +196,4 @@ int main() {
   mi_stats_print(NULL);
   return 0;
 }
+
diff --git a/test/main-override.cpp b/test/main-override.cpp
index 4bc91ae8..e006ad27 100644
--- a/test/main-override.cpp
+++ b/test/main-override.cpp
@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <assert.h>
 #include <string.h>
+#include <stdint.h>
 
 #include <mimalloc.h>
 #include <new>
@@ -66,3 +67,5 @@ public:
 };
 
 static Static s = Static();
+
+