diff --git a/libretro-common/file/nbio/nbio_windowsmmap.c b/libretro-common/file/nbio/nbio_windowsmmap.c
new file mode 100644
index 0000000000..458e3b1d9e
--- /dev/null
+++ b/libretro-common/file/nbio/nbio_windowsmmap.c
@@ -0,0 +1,113 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <file/nbio.h>
+
+#include <windows.h>
+
+struct nbio_t
+{
+   HANDLE file;
+   bool is_write;
+   size_t len;
+   void* ptr;
+};
+
+#define FILE_SHARE_ALL (FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE)
+struct nbio_t* nbio_open(const char * filename, unsigned mode)
+{
+   static const DWORD dispositions[] = { OPEN_EXISTING, CREATE_ALWAYS, OPEN_ALWAYS, OPEN_EXISTING, CREATE_ALWAYS };
+   
+   bool is_write = (mode == NBIO_WRITE || mode == NBIO_UPDATE || mode == BIO_WRITE);
+   DWORD access = (is_write ? GENERIC_READ|GENERIC_WRITE : GENERIC_READ);
+   HANDLE file = CreateFile(filename, access, FILE_SHARE_ALL, NULL, dispositions[mode], FILE_ATTRIBUTE_NORMAL, NULL);
+   
+   HANDLE mem;
+   
+   void* ptr;
+   LARGE_INTEGER len;
+   struct nbio_t* handle;
+   
+   if (file == INVALID_HANDLE_VALUE) return NULL;
+   
+   GetFileSizeEx(file, &len);
+   
+   mem = CreateFileMapping(file, NULL, is_write ? PAGE_READWRITE : PAGE_READONLY, 0, 0, NULL);
+   ptr = MapViewOfFile(mem, is_write ? (FILE_MAP_READ|FILE_MAP_WRITE) : FILE_MAP_READ, 0, 0, len.QuadPart);
+   CloseHandle(mem);
+   
+   handle = malloc(sizeof(struct nbio_t));
+   handle->file = file;
+   handle->is_write = is_write;
+   handle->len = len.QuadPart;
+   handle->ptr = ptr;
+   return handle;
+}
+
+void nbio_begin_read(struct nbio_t* handle)
+{
+   /* not needed */
+}
+
+void nbio_begin_write(struct nbio_t* handle)
+{
+   /* not needed */
+}
+
+bool nbio_iterate(struct nbio_t* handle)
+{
+   return true; /* not needed */
+}
+
+void nbio_resize(struct nbio_t* handle, size_t len)
+{
+   LARGE_INTEGER len_li;
+   HANDLE mem;
+   
+   if (len < handle->len)
+   {
+      /* this works perfectly fine if this check is removed, but it won't work on other nbio implementations */
+      /* therefore, it's blocked so nobody accidentally relies on it */
+      puts("ERROR - attempted file shrink operation, not implemented");
+      abort();
+   }
+   
+   len_li.QuadPart = len;
+   SetFilePointerEx(handle->file, len_li, NULL, FILE_BEGIN);
+   
+   if (!SetEndOfFile(handle->file))
+   {
+      puts("ERROR - couldn't resize file (SetEndOfFile)");
+      abort(); /* this one returns void and I can't find any other way for it to report failure */
+   }
+   handle->len = len;
+   
+   UnmapViewOfFile(handle->ptr);
+   mem = CreateFileMapping(handle->file, NULL, handle->is_write ? PAGE_READWRITE : PAGE_READONLY, 0, 0, NULL);
+   handle->ptr = MapViewOfFile(mem, handle->is_write ? (FILE_MAP_READ|FILE_MAP_WRITE) : FILE_MAP_READ, 0, 0, len);
+   CloseHandle(mem);
+   
+   if (handle->ptr == NULL)
+   {
+      puts("ERROR - couldn't resize file (MapViewOfFile)");
+      abort();
+   }
+}
+
+void* nbio_get_ptr(struct nbio_t* handle, size_t* len)
+{
+   if (len) *len = handle->len;
+   return handle->ptr;
+}
+
+void nbio_cancel(struct nbio_t* handle)
+{
+   /* not needed */
+}
+
+void nbio_free(struct nbio_t* handle)
+{
+   CloseHandle(handle->file);
+   UnmapViewOfFile(handle->ptr);
+   free(handle);
+}