diff --git a/2021/day16/day16_rs/src/main.rs b/2021/day16/day16_rs/src/main.rs
index 104b08d..9553850 100644
--- a/2021/day16/day16_rs/src/main.rs
+++ b/2021/day16/day16_rs/src/main.rs
@@ -7,7 +7,7 @@ use std::{
 
 use nom::{
     bits::complete as bits,
-    multi::{many0, many_m_n}, Offset,
+    multi::{many0, many_m_n}, error::ParseError, Offset,
 };
 use nom::{combinator::map, sequence::pair};
 use parsers::fold_till;
@@ -15,7 +15,7 @@ use parsers::fold_till;
 mod parsers;
 
 type Input<'a> = (&'a [u8], usize);
-type IResult<'a, T> = nom::IResult<Input<'a>, T>;
+type IResult<'a, T, E> = nom::IResult<Input<'a>, T, E>;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 struct Packet {
@@ -24,7 +24,7 @@ struct Packet {
 }
 
 impl Packet {
-    pub fn parse(i: Input) -> IResult<Packet> {
+    pub fn parse<'a, E: ParseError<Input<'a>>>(i: Input<'a>) -> IResult<'a, Packet, E> {
         map(
             pair(bits::take(3_usize), PacketType::parse),
             |(version, typ)| Packet { version, typ },
@@ -52,7 +52,7 @@ enum PacketType {
 }
 
 impl PacketType {
-    pub fn parse(i: Input) -> IResult<PacketType> {
+    pub fn parse<'a, E: ParseError<Input<'a>>>(i: Input<'a>) -> IResult<'a, PacketType, E> {
         let (i, operator) = map(bits::take(3_usize), |type_id: u8| {
             Operator::try_from(type_id)
         })(i)?;
@@ -68,14 +68,14 @@ impl PacketType {
         }
     }
 
-    fn parse_sub_packets(i: Input) -> IResult<Vec<Packet>> {
+    fn parse_sub_packets<'a, E: ParseError<Input<'a>>>(i: Input<'a>) -> IResult<'a, Vec<Packet>, E> {
         enum LengthType {
             Bits(usize),
             Packets(usize),
         }
 
         impl LengthType {
-            pub fn parse(i: Input) -> IResult<Self> {
+            pub fn parse<'a, E: ParseError<Input<'a>>>(i: Input<'a>) -> IResult<'a, Self, E> {
                 let (i, length_type_id) = bits::take(1_usize)(i)?;
                 match length_type_id {
                     0 => map(bits::take(15_usize), LengthType::Bits)(i),
@@ -110,7 +110,7 @@ impl PacketType {
         }
     }
 
-    fn parse_literal_value(i: Input) -> IResult<usize> {
+    fn parse_literal_value<'a, E: ParseError<Input<'a>>>(i: Input<'a>) -> IResult<'a, usize, E> {
         fold_till(
             pair(bits::take(1_usize), bits::take(4_usize)),
             || 0,
@@ -199,7 +199,7 @@ fn main() {
         .flatten()
         .collect();
 
-    let packet = Packet::parse((&bytes, 0)).unwrap().1;
+    let packet = Packet::parse::<nom::error::Error<_>>((&bytes, 0)).unwrap().1;
     println!("{}", packet.version_sum());
     println!("{}", packet.typ.evaluate());
 }