diff --git a/logical_type.go b/logical_type.go
index 3a811fc..e997ef4 100644
--- a/logical_type.go
+++ b/logical_type.go
@@ -250,11 +250,8 @@ func nativeFromDecimalBytes(fn toNativeFn, precision, scale int) toNativeFn {
 		}
 		i := big.NewInt(0)
 		fromSignedBytes(i, bs)
-		if i.BitLen() > 64 {
-			// Avro spec specifies we return underlying type if the logicalType is invalid
-			return d, b, err
-		}
-		r := big.NewRat(i.Int64(), int64(math.Pow10(scale)))
+		r := new(big.Rat)
+		r.SetFrac(i, big.NewInt(int64(math.Pow10(scale))))
 		return r, b, nil
 	}
 }
diff --git a/logical_type_test.go b/logical_type_test.go
index 6591b51..24a2465 100644
--- a/logical_type_test.go
+++ b/logical_type_test.go
@@ -97,6 +97,13 @@ func TestDecimalBytesLogicalTypeEncode(t *testing.T) {
 	testBinaryCodecPass(t, schema, big.NewRat(617, 50), []byte("\x04\x04\xd2"))
 	testBinaryCodecPass(t, schema, big.NewRat(-617, 50), []byte("\x04\xfb\x2e"))
 	testBinaryCodecPass(t, schema, big.NewRat(0, 1), []byte("\x02\x00"))
+	schema0scale := `{"type": "bytes", "logicalType": "decimal", "precision": 100, "scale": 0}`
+	r1, _ := new(big.Rat).SetString("9223372036854775808") // 2^63
+	testBinaryCodecPass(t, schema0scale, r1, []byte("\x12\x00\x80\x00\x00\x00\x00\x00\x00\x00"))
+	r2, _ := new(big.Rat).SetString("18446744073709551615") // 2^64 - 1
+	testBinaryCodecPass(t, schema0scale, r2, []byte("\x12\x00\xff\xff\xff\xff\xff\xff\xff\xff"))
+	r3, _ := new(big.Rat).SetString("170141183460469231731687303715884105728")
+	testBinaryCodecPass(t, schema0scale, r3, []byte("\x22\x00\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"))
 }
 
 func TestDecimalFixedLogicalTypeEncode(t *testing.T) {