--- japron/gmp/gmp_Mpfr.c.orig	2019-11-10 07:33:31.000000000 -0700
+++ japron/gmp/gmp_Mpfr.c	2020-01-17 09:08:16.852531901 -0700
@@ -824,10 +824,23 @@ JNIEXPORT jint JNICALL Java_gmp_Mpfr_cbr
 JNIEXPORT jint JNICALL Java_gmp_Mpfr_root
   (JNIEnv *env, jobject o1, jobject o2, jint i, jint p)
 {
+#if MPFR_VERSION_MAJOR >= 4
+  mpfr_ptr mpfr1, mpfr2;
+#endif
   check_nonnull(o1,0);
   check_nonnull(o2,0);
   check_positive(i,0);
+#if MPFR_VERSION_MAJOR >= 4
+  mpfr1 = as_mpfr(o1);
+  mpfr2 = as_mpfr(o2);
+  if (mpfr_zero_p(mpfr2)) {
+    mpfr_set_zero(mpfr1, mpfr_sgn(mpfr2));
+    return 0;
+  }
+  return mpfr_rootn_ui(mpfr1, mpfr2, i, p);
+#else
   return mpfr_root(as_mpfr(o1), as_mpfr(o2), i, p);
+#endif
 }
 
 /*