diff --git a/dlls/msvcrt/heap.c b/dlls/msvcrt/heap.c
index 74e7b371aa2..3ee2048abe0 100644
--- a/dlls/msvcrt/heap.c
+++ b/dlls/msvcrt/heap.c
@@ -37,6 +37,8 @@ typedef void (*MSVCRT_new_handler_func)(unsigned long size);
 static MSVCRT_new_handler_func MSVCRT_new_handler;
 static int MSVCRT_new_mode;
 
+/* FIXME - According to documentation it should be 8*1024, at runtime it returns 16 */ 
+static unsigned int MSVCRT_amblksiz = 16;
 
 /*********************************************************************
  *		??2@YAPAXI@Z (MSVCRT.@)
@@ -281,3 +283,11 @@ void* MSVCRT_realloc(void* ptr, MSVCRT_size_t size)
   MSVCRT_free(ptr);
   return NULL;
 }
+
+/*********************************************************************
+ *		__p__amblksiz (MSVCRT.@)
+ */
+unsigned int* __p__amblksiz(void)
+{
+  return &MSVCRT_amblksiz;
+}
diff --git a/dlls/msvcrt/msvcrt.spec b/dlls/msvcrt/msvcrt.spec
index 101b8ca9ffe..8ca03658f0a 100644
--- a/dlls/msvcrt/msvcrt.spec
+++ b/dlls/msvcrt/msvcrt.spec
@@ -107,7 +107,7 @@
 @ cdecl __p___wargv()
 @ cdecl __p___winitenv()
 @ cdecl __p__acmdln()
-@ stub __p__amblksiz #()
+@ cdecl __p__amblksiz()
 @ cdecl __p__commode()
 @ cdecl __p__daylight() MSVCRT___p__daylight
 @ stub __p__dstbias #()
diff --git a/include/msvcrt/malloc.h b/include/msvcrt/malloc.h
index 3c1d09e2c12..1e36d16e845 100644
--- a/include/msvcrt/malloc.h
+++ b/include/msvcrt/malloc.h
@@ -50,6 +50,9 @@ typedef struct _heapinfo
 } _HEAPINFO;
 #endif /* _HEAPINFO_DEFINED */
 
+extern unsigned int* __p__amblksiz(void);
+#define _amblksiz (*__p__amblksiz());
+
 #ifdef __cplusplus
 extern "C" {
 #endif