diff --git a/numeric.c b/numeric.c
index 21e8eeeb8e..9a9b8d0b44 100644
--- a/numeric.c
+++ b/numeric.c
@@ -721,7 +721,10 @@ num_zero_p(VALUE num)
 	}
     }
     else if (RB_TYPE_P(num, T_BIGNUM)) {
-	return rb_bigzero_p(num);
+	if (rb_bigzero_p(num)) {
+	    /* this should not happen usually */
+	    return Qtrue;
+	}
     }
     else if (rb_equal(num, INT2FIX(0))) {
 	return Qtrue;
diff --git a/test/-ext-/bignum/test_bigzero.rb b/test/-ext-/bignum/test_bigzero.rb
index 8529e54456..43a99b01a3 100644
--- a/test/-ext-/bignum/test_bigzero.rb
+++ b/test/-ext-/bignum/test_bigzero.rb
@@ -10,5 +10,11 @@ class TestBignum < Test::Unit::TestCase
         assert_equal(0, Bug::Bignum.zero(i), "#{bug8204} Bignum.zero(#{i})")
       end
     end
+
+    def test_zero?
+      (0..10).each do |i|
+        assert_equal(true, Bug::Bignum.zero(i).zero?)
+      end
+    end
   end
 end