diff --git a/src/util/uint.rs b/src/util/uint.rs
index 91b6b71d..f58bdcdb 100644
--- a/src/util/uint.rs
+++ b/src/util/uint.rs
@@ -494,7 +494,7 @@ construct_uint!(Uint256, 4);
 construct_uint!(Uint128, 2);
 
 /// Invalid slice length
-#[derive(Debug, PartialEq, PartialOrd, Clone, Copy, Hash)]
+#[derive(Debug, PartialEq, Eq, PartialOrd, Clone, Copy, Hash)]
 /// Invalid slice length
 pub struct ParseLengthError {
     /// The length of the slice de-facto
@@ -509,6 +509,8 @@ impl ::std::fmt::Display for ParseLengthError {
     }
 }
 
+impl ::std::error::Error for ParseLengthError {}
+
 impl Uint256 {
     /// Increment by 1
     #[inline]