diff --git a/src/decode/codecs/mod.rs b/src/decode/codecs/mod.rs
index 8d28350..a1b2ad7 100644
--- a/src/decode/codecs/mod.rs
+++ b/src/decode/codecs/mod.rs
@@ -7,8 +7,8 @@ use std::error::Error;
 use crate::util;
 
 pub trait Decoder {
-    fn write_nalu(&mut self, nalu: util::NALUPacket) -> Result<(), Box<dyn Error + Send + Sync>>;
-    fn write_loop(&mut self, chan_in: mpsc::Receiver<util::NALUPacket>, err_in: mpsc::Sender<Box<dyn Error + Send + Sync>>) {
+    fn write_nalu(&self, nalu: util::NALUPacket) -> Result<(), Box<dyn Error + Send + Sync>>;
+    fn write_loop(&self, chan_in: mpsc::Receiver<util::NALUPacket>, err_in: mpsc::Sender<Box<dyn Error + Send + Sync>>) {
         loop {
             let nalu = match chan_in.recv() {
                 Ok(x) => x,
@@ -20,8 +20,8 @@ pub trait Decoder {
             }
         }
     }
-    fn read_raw(&mut self) -> Result<util::RawMedia, Box<dyn Error + Send + Sync>>;
-    fn read_loop(&mut self, chan_out: mpsc::Sender<util::RawMedia>, err_in: mpsc::Sender<Box<dyn Error + Send + Sync>>) {
+    fn read_raw(&self) -> Result<util::RawMedia, Box<dyn Error + Send + Sync>>;
+    fn read_loop(&self, chan_out: mpsc::Sender<util::RawMedia>, err_in: mpsc::Sender<Box<dyn Error + Send + Sync>>) {
         loop {
             let raw_sample = match self.read_raw() {
                 Ok(x) => x,