1 files changed, 2 insertions, 1 deletions
diff --git a/acos.c b/acos.c
index 1210f2c49..093734b65 100644
--- a/acos.c
+++ b/acos.c
@@ -108,7 +108,8 @@ mpfr_acos (mpfr_ptr acos, mpfr_srcptr x, mp_rnd_t rnd_mode)
       mpfr_div_2ui (tmp, tmp, 1, GMP_RNDN);
       mpfr_sub (arcc, tmp, arcc, GMP_RNDN);
 
-      if (mpfr_can_round (arcc, realprec, GMP_RNDN, rnd_mode, MPFR_PREC(acos)))
+      if (mpfr_can_round (arcc, realprec, GMP_RNDN, GMP_RNDZ,
+                          MPFR_PREC(acos) + (rnd_mode == GMP_RNDN)))
         {
           inexact = mpfr_set (acos, arcc, rnd_mode);
           good = 1;