diff --git a/libc/include/sys/linux-unistd.h b/libc/include/sys/linux-unistd.h
index 6bd9ac7..a439e0f 100644
--- a/libc/include/sys/linux-unistd.h
+++ b/libc/include/sys/linux-unistd.h
@@ -53,7 +53,7 @@
 ssize_t          read (int, void*, size_t);
 ssize_t          write (int, const void*, size_t);
 ssize_t          __pread64 (int, void *, size_t, off_t, off_t);
-ssize_t          __pwrite64 (int, void *, size_t, off_t, off_t);
+ssize_t          __pwrite64 (int, const void *, size_t, off_t, off_t);
 int              __open (const char*, int, mode_t);
 int              __openat (int, const char*, int, mode_t);
 int              close (int);