--- src/mul.c.orig	2015-02-16 21:37:30.000000000 +0900
+++ src/mul.c	2021-12-29 10:17:55.517367000 +0900
@@ -172,7 +172,7 @@
 
 
 static int
-mpfr_fmma (mpfr_ptr z, mpfr_srcptr a, mpfr_srcptr b, mpfr_srcptr c,
+_mpfr_fmma (mpfr_ptr z, mpfr_srcptr a, mpfr_srcptr b, mpfr_srcptr c,
            mpfr_srcptr d, int sign, mpfr_rnd_t rnd)
 {
    /* Computes z = ab+cd if sign >= 0, or z = ab-cd if sign < 0.
@@ -337,9 +337,9 @@
    else
       rop [0] = z [0];
 
-   inex = MPC_INEX (mpfr_fmma (mpc_realref (rop), mpc_realref (x), mpc_realref (y), mpc_imagref (x),
+   inex = MPC_INEX (_mpfr_fmma (mpc_realref (rop), mpc_realref (x), mpc_realref (y), mpc_imagref (x),
                                mpc_imagref (y), -1, MPC_RND_RE (rnd)),
-                    mpfr_fmma (mpc_imagref (rop), mpc_realref (x), mpc_imagref (y), mpc_imagref (x),
+                    _mpfr_fmma (mpc_imagref (rop), mpc_realref (x), mpc_imagref (y), mpc_imagref (x),
                                mpc_realref (y), +1, MPC_RND_IM (rnd)));
 
    mpc_set (z, rop, MPC_RNDNN);