diff --git a/implementations/rust/src/value/decoder.rs b/implementations/rust/src/value/decoder.rs
index 95e9f44..c4f337c 100644
--- a/implementations/rust/src/value/decoder.rs
+++ b/implementations/rust/src/value/decoder.rs
@@ -106,7 +106,7 @@ impl<'a, 'b, R: Read> Decoder<'a, 'b, R> {
         match *self.buf {
             Some(Some(v)) => Ok(v),
             Some(None) => Err(Error::Eof),
-            None => panic!()
+            None => unreachable!()
         }
     }
 
@@ -118,7 +118,7 @@ impl<'a, 'b, R: Read> Decoder<'a, 'b, R> {
 
     pub fn readbytes(&mut self, n: usize) -> Result<Vec<u8>> {
         if (*self.buf).is_some() {
-            panic!();
+            unreachable!();
         }
         let mut bs = vec![0; n];
         match self.read.read_exact(&mut bs) {
@@ -280,7 +280,7 @@ impl<'a, 'b, R: Read> Decoder<'a, 'b, R> {
                 let n = if arg > 12 { i32::from(arg) - 16 } else { i32::from(arg) };
                 Ok(Value::from(n).wrap())
             }
-            (Op::Misc(_), _) => panic!(),
+            (Op::Misc(_), _) => unreachable!(),
             (Op::Atom(minor), arg) => {
                 let count = self.wirelength(arg)?;
                 Self::decodebinary(minor, self.readbytes(count)?)