diff --git a/conf.h.in b/conf.h.in
index ecd1811..48de4cb 100644
--- a/conf.h.in
+++ b/conf.h.in
@@ -60,6 +60,16 @@
 #define USE_MMAP 0
 #define HAVE_MUNMAP 0
 
+/*
+ * On Windows, use VirtualAlloc() to allocate memory and use VirtualFree
+ * to deallocate it. To be absolutely sure, try to find it in one of the
+ * two sets of header files.
+ */
+#define HAVE_DECL_VIRTUALALLOC 0
+#define HAVE_DECL_VIRTUALFREE 0
+#define HAVE_VIRTUALALLOC_MEMORYAPI_H 0
+#define HAVE_VIRTUALALLOC_WINDOWS_H 0
+
 /*
  * This is the basic block size in bits.  If possible, the configure
  * script will set this to be the value returned by the getpagesize()
diff --git a/configure.ac b/configure.ac
index a5295f1..7d84310 100644
--- a/configure.ac
+++ b/configure.ac
@@ -345,7 +345,31 @@ AC_MSG_NOTICE([important functionality])
 
 AC_CHECK_FUNCS(mmap munmap sbrk)
 
-if test "x$ac_cv_func_mmap" != "xyes" && test "x$ac_cv_func_sbrk" != "xyes"; then
+ac_cv_target_win32=no
+AC_MSG_CHECKING([for VirtualAlloc in <windows.h> (Windows)])
+AC_CHECK_DECLS(
+ [[VirtualAlloc(LPVOID, SIZE_T, DWORD, DWORD)],
+  [VirtualFree(LPVOID, SIZE_T, DWORD)]],
+ [ ac_cv_target_win32=yes; AC_DEFINE(HAVE_VIRTUALALLOC_WINDOWS_H) ],
+ [
+  AC_MSG_CHECKING([for VirtualAlloc in <windows.h>, <memoryapi.h> (Windows)])
+  AC_CHECK_DECLS(
+   [[VirtualAlloc(LPVOID, SIZE_T, DWORD, DWORD)],
+    [VirtualFree(LPVOID, SIZE_T, DWORD)]],
+   [ ac_cv_target_win32=yes; AC_DEFINE(HAVE_VIRTUALALLOC_MEMORYAPI_H) ],
+   [ ac_cv_target_win32=no ],
+   [[#define WIN32_LEAN_AND_MEAN
+     #include <windows.h>
+     #include <memoryapi.h>]]
+  )
+ ],
+ [[#define WIN32_LEAN_AND_MEAN
+   #include <windows.h>]]
+)
+
+if test "x$ac_cv_func_mmap" != "xyes" && test "x$ac_cv_func_sbrk" != "xyes" && \
+	test "x$ac_cv_target_win32" != "xyes";
+then
 	AC_MSG_WARN()
 	AC_MSG_WARN(no mmap nor sbrk function.  See INTERNAL_MEMORY_SPACE in settings.dist.)
 	AC_MSG_WARN()
diff --git a/dmalloc_t.c b/dmalloc_t.c
index 13143b2..e9417db 100644
--- a/dmalloc_t.c
+++ b/dmalloc_t.c
@@ -61,7 +61,7 @@
 #define INTER_CHAR		'i'
 #define DEFAULT_ITERATIONS	10000
 #define MAX_POINTERS		1024
-#if HAVE_SBRK == 0 && HAVE_MMAP == 0
+#if HAVE_SBRK == 0 && HAVE_MMAP == 0 && (HAVE_DECL_VIRTUALALLOC == 0 || HAVE_DECL_VIRTUALFREE == 0)
 /* if we have a small memory area then just take 1/10 of the internal space */
 #define MAX_ALLOC		(INTERNAL_MEMORY_SPACE / 10)
 #else
diff --git a/heap.c b/heap.c
index 210c29e..8edcd3c 100644
--- a/heap.c
+++ b/heap.c
@@ -24,12 +24,22 @@
  * heap as well as reporting the current position of the heap.
  */
 
+#include "conf.h"
+
 #if HAVE_SYS_TYPES_H
 #  include <sys/types.h>
 #endif
 #if HAVE_SYS_MMAN_H
 #  include <sys/mman.h>				/* for mmap stuff */
 #endif
+#if HAVE_VIRTUALALLOC_WINDOWS_H
+#  define WIN32_LEAN_AND_MEAN
+#  include <windows.h>
+#elif HAVE_VIRTUALALLOC_MEMORYAPI_H
+#  define WIN32_LEAN_AND_MEAN
+#  include <windows.h>
+#  include <memoryapi.h>
+#endif
 
 #define DMALLOC_DISABLE
 
@@ -95,6 +105,9 @@ static	void	*heap_extend(const int incr)
 #else
 #if HAVE_SBRK
   ret = sbrk(incr);
+#elif HAVE_DECL_VIRTUALALLOC && HAVE_DECL_VIRTUALFREE
+  ret = VirtualAlloc(NULL, incr, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
+  if (!ret) ret = SBRK_ERROR;
 #endif /* if HAVE_SBRK */
 #endif /* if not HAVE_MMAP && USE_MMAP */
 #endif /* if not INTERNAL_MEMORY_SPACE */
@@ -149,6 +162,12 @@ static	void	heap_release(void *addr, const int size)
     dmalloc_message("munmap failed to release heap memory %p, size %d",
 		    addr, size);
   }
+#elif HAVE_DECL_VIRTUALALLOC && HAVE_DECL_VIRTUALFREE
+  /* NB: Assuming that heap_release is always called with the same size as
+  ** heap_extend. WinAPI requires the second parameter to VirtualFree
+  ** to be 0 to avoid reserving and then abandoning blocks of uncommitted
+  ** address space. */
+  VirtualFree(addr, 0, MEM_RELEASE);
 #else
   /* no-op */
 #endif /* if not HAVE_MMAP && USE_MMAP */
diff --git a/settings.dist b/settings.dist
index eec24fc..3535ae9 100644
--- a/settings.dist
+++ b/settings.dist
@@ -387,7 +387,7 @@
  * HAVE_MMAP are 0.  Please send me email with any problems or
  * comments on this feature.
  */
-#if HAVE_SBRK == 0 && HAVE_MMAP == 0
+#if HAVE_SBRK == 0 && HAVE_MMAP == 0 && (HAVE_DECL_VIRTUALALLOC == 0 || HAVE_DECL_VIRTUALFREE == 0)
 #define INTERNAL_MEMORY_SPACE (1024 * 1024)
 #endif