diff -urN a/lib/file/fileIOPosix.c b/lib/file/fileIOPosix.c
--- a/lib/file/fileIOPosix.c
+++ b/lib/file/fileIOPosix.c
@@ -206,10 +206,10 @@
        * the symbols (and anyone building XOPEN<700 gets nothing).
        */
       extern ssize_t preadv64(int fd, const struct iovec *iov, int iovcnt,
-                          __off64_t offset) __attribute__ ((weak));
+                          off64_t offset) __attribute__ ((weak));
 
       extern ssize_t pwritev64(int fd, const struct iovec *iov, int iovcnt,
-                          __off64_t offset) __attribute__ ((weak));
+                          off64_t offset) __attribute__ ((weak));
    #else
       #error "Large file support unavailable. Aborting."
    #endif
