diff --git a/core/src/muxing.rs b/core/src/muxing.rs
index 9987ee964a9d..0c1b9bffd766 100644
--- a/core/src/muxing.rs
+++ b/core/src/muxing.rs
@@ -81,7 +81,7 @@ pub trait StreamMuxer {
     type OutboundSubstream;
 
     /// Error type of the muxer
-    type Error;
+    type Error: std::error::Error + Send + Sync + 'static;
 
     /// Polls for a connection-wide event.
     ///
diff --git a/core/src/muxing/boxed.rs b/core/src/muxing/boxed.rs
index d6ac3ef735b4..f53f4d00983e 100644
--- a/core/src/muxing/boxed.rs
+++ b/core/src/muxing/boxed.rs
@@ -39,7 +39,6 @@ impl<T> StreamMuxer for Wrap<T>
 where
     T: StreamMuxer,
     T::Substream: AsyncRead + AsyncWrite + Send + Unpin + 'static,
-    T::Error: Into<Box<dyn Error + Send + Sync>>,
 {
     type Substream = SubstreamBox;
     type OutboundSubstream = usize; // TODO: use a newtype
@@ -100,7 +99,7 @@ where
 
 fn into_io_error<E>(err: E) -> io::Error
 where
-    E: Into<Box<dyn Error + Send + Sync>>,
+    E: Error + Send + Sync + 'static,
 {
     io::Error::new(io::ErrorKind::Other, err)
 }
@@ -112,7 +111,6 @@ impl StreamMuxerBox {
         T: StreamMuxer + Send + Sync + 'static,
         T::OutboundSubstream: Send,
         T::Substream: AsyncRead + AsyncWrite + Send + Unpin + 'static,
-        T::Error: Into<Box<dyn Error + Send + Sync>>,
     {
         let wrap = Wrap {
             inner: muxer,
diff --git a/core/src/transport/upgrade.rs b/core/src/transport/upgrade.rs
index 9c7fbb4fd005..a20f72129719 100644
--- a/core/src/transport/upgrade.rs
+++ b/core/src/transport/upgrade.rs
@@ -302,7 +302,6 @@ impl<T> Multiplexed<T> {
         M: StreamMuxer + Send + Sync + 'static,
         M::Substream: AsyncRead + AsyncWrite + Send + Unpin + 'static,
         M::OutboundSubstream: Send + 'static,
-        M::Error: Into<Box<dyn Error + Send + Sync>>,
     {
         boxed(self.map(|(i, m), _| (i, StreamMuxerBox::new(m))))
     }