diff -ruN mpfr-4.0.0/src/mpfr.h mpfr-4.0.0-new/src/mpfr.h
--- mpfr-4.0.0/src/mpfr.h	2017-12-23 10:17:50.000000000 +0000
+++ mpfr-4.0.0-new/src/mpfr.h	2018-01-12 08:14:38.464407500 +0000
@@ -51,6 +51,8 @@
 
 #include <gmp.h>
 
+#define __gmp_const const
+
 /* Avoid some problems with macro expansion if the user defines macros
    with the same name as keywords. By convention, identifiers and macro
    names starting with mpfr_ are reserved by MPFR. */