diff --git a/src/decode.rs b/src/decode.rs
index 4f8cd03..0a7c8e2 100644
--- a/src/decode.rs
+++ b/src/decode.rs
@@ -23,8 +23,7 @@ use core::{self, fmt};
 
 /// Possible decoding errors.
 ///
-/// **Note**: The `std` feature is required for the `std::error::Error` impl and the conversion to
-/// `std::io::Error`.
+/// **Note**: The `std` feature is required for the conversion to `std::io::Error`.
 #[non_exhaustive]
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum Error {
@@ -46,9 +45,7 @@ impl fmt::Display for Error {
     }
 }
 
-/// Only available when the feature `std` is present.
-#[cfg(feature = "std")]
-impl std::error::Error for Error {}
+impl core::error::Error for Error {}
 
 /// Only available when the feature `std` is present.
 #[cfg(feature = "std")]
diff --git a/src/io.rs b/src/io.rs
index f730918..0ba6bfa 100644
--- a/src/io.rs
+++ b/src/io.rs
@@ -59,20 +59,20 @@ gen! {
 #[derive(Debug)]
 pub enum ReadError {
     Io(io::Error),
-    Decode(decode::Error)
+    Decode(decode::Error),
 }
 
 impl fmt::Display for ReadError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             ReadError::Io(e) => write!(f, "i/o error: {}", e),
-            ReadError::Decode(e) => write!(f, "decode error: {}", e)
+            ReadError::Decode(e) => write!(f, "decode error: {}", e),
         }
     }
 }
 
-impl std::error::Error for ReadError {
-    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+impl core::error::Error for ReadError {
+    fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
         if let ReadError::Io(e) = self {
             Some(e)
         } else {