diff --git a/mrbgems/mruby-bigint/core/bigint.c b/mrbgems/mruby-bigint/core/bigint.c
index fea4782a49..e3856562be 100644
--- a/mrbgems/mruby-bigint/core/bigint.c
+++ b/mrbgems/mruby-bigint/core/bigint.c
@@ -1380,8 +1380,10 @@ mrb_bint_powm(mrb_state *mrb, mrb_value x, mrb_int exp, mrb_value mod)
   switch (mrb_type(mod)) {
   case MRB_TT_INTEGER:
     {
+      mrb_int m = mrb_integer(mod);
+      if (m == 0) mrb_int_zerodiv(mrb);
       struct RBigint *b2 = bint_new(mrb);
-      struct RBigint *b3 = bint_new_int(mrb, mrb_integer(mod));
+      struct RBigint *b3 = bint_new_int(mrb, m);
       mpz_powm(mrb, &b2->mp, &b->mp, exp, &b3->mp);
       return mrb_obj_value(b3);
     }
@@ -1389,6 +1391,7 @@ mrb_bint_powm(mrb_state *mrb, mrb_value x, mrb_int exp, mrb_value mod)
     {
       struct RBigint *b2 = bint_new(mrb);
       struct RBigint *b3 = RBIGINT(mod);
+      if (uzero(&b3->mp)) mrb_int_zerodiv(mrb);
       mpz_powm(mrb, &b2->mp, &b->mp, exp, &b3->mp);
       return bint_norm(mrb, b3);
     }