diff --git a/expat/xmlwf/unixfilemap.c b/expat/xmlwf/unixfilemap.c
index d0ce9cc6..0cfd976b 100644
--- a/expat/xmlwf/unixfilemap.c
+++ b/expat/xmlwf/unixfilemap.c
@@ -93,8 +93,7 @@ filemap(const tchar *name,
     close(fd);
     return 1;
   }
-  p = (void *)mmap((void *)0, (size_t)nbytes, PROT_READ, MAP_FILE | MAP_PRIVATE,
-                   fd, (off_t)0);
+  p = mmap((void *)0, nbytes, PROT_READ, MAP_FILE | MAP_PRIVATE, fd, (off_t)0);
   if (p == (void *)-1) {
     tperror(name);
     close(fd);