diff --git a/primitive-types/src/error.rs b/primitive-types/src/error.rs
deleted file mode 100644
index 027149f..0000000
--- a/primitive-types/src/error.rs
+++ /dev/null
@@ -1,72 +0,0 @@
-// Copyright 2015-2019 Parity Technologies
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-// TODO: Remove TryFrom and TryInto when Rust trait is stablized
-// https://github.com/paritytech/parity-common/issues/103
-//! Error, `TryFrom` and `TryInto` trait, should be removed when standard library stablize those.
-
-/// Error type for conversion.
-pub enum Error {
-    /// Overflow encountered.
-    Overflow,
-}
-
-/// An attempted conversion that consumes `self`, which may or may not be
-/// expensive.
-///
-/// Library authors should not directly implement this trait, but should prefer
-/// implementing the [`TryFrom`] trait, which offers greater flexibility and
-/// provides an equivalent `TryInto` implementation for free, thanks to a
-/// blanket implementation in the standard library. For more information on this,
-/// see the documentation for [`Into`].
-///
-/// [`TryFrom`]: trait.TryFrom.html
-/// [`Into`]: trait.Into.html
-pub trait TryInto<T>: Sized {
-    /// The type returned in the event of a conversion error.
-    type Error;
-
-    /// Performs the conversion.
-    fn try_into(self) -> Result<T, Self::Error>;
-}
-
-/// Attempt to construct `Self` via a conversion.
-pub trait TryFrom<T>: Sized {
-    /// The type returned in the event of a conversion error.
-    type Error;
-
-    /// Performs the conversion.
-    fn try_from(value: T) -> Result<Self, Self::Error>;
-}
-
-// TryFrom implies TryInto
-impl<T, U> TryInto<U> for T
-where
-    U: TryFrom<T>,
-{
-    type Error = U::Error;
-
-    fn try_into(self) -> Result<U, U::Error> {
-        U::try_from(self)
-    }
-}
-
-pub enum Never {}
-
-// Infallible conversions are semantically equivalent to fallible conversions
-// with an uninhabited error type.
-impl<T, U> TryFrom<U> for T
-where
-    T: From<U>,
-{
-    type Error = Never;
-
-    fn try_from(value: U) -> Result<Self, Self::Error> {
-        Ok(T::from(value))
-    }
-}
diff --git a/primitive-types/src/lib.rs b/primitive-types/src/lib.rs
index d057043..91f8571 100644
--- a/primitive-types/src/lib.rs
+++ b/primitive-types/src/lib.rs
@@ -25,20 +25,30 @@ extern crate uint;
 #[macro_use]
 extern crate fixed_hash;
 
+use ustd::convert::TryFrom;
+
+#[cfg(feature = "serde")]
+pub use impl_serde::serde;
 #[cfg(feature = "serde")]
 use impl_serde::{impl_fixed_hash_serde, impl_uint_serde};
 
+#[cfg(feature = "codec")]
+pub use impl_codec::codec;
 #[cfg(feature = "codec")]
 use impl_codec::{impl_fixed_hash_codec, impl_fixed_hash_codec_ext, impl_uint_codec};
 
+#[cfg(feature = "rlp")]
+pub use impl_rlp::rlp;
 #[cfg(feature = "rlp")]
 use impl_rlp::{impl_fixed_hash_rlp, impl_uint_rlp};
 
-mod error;
-#[cfg(test)]
 mod tests;
 
-pub use self::error::{Error, Never, TryFrom, TryInto};
+/// Error type for conversion.
+pub enum Error {
+    /// Overflow encountered.
+    Overflow,
+}
 
 // ================================================================================================
 // Unsigned Integer -- U64, U128, U256, U512.
diff --git a/primitive-types/src/tests.rs b/primitive-types/src/tests.rs
index 384416b..49a3feb 100644
--- a/primitive-types/src/tests.rs
+++ b/primitive-types/src/tests.rs
@@ -1,3 +1,5 @@
+#![cfg(test)]
+
 #[cfg(any(feature = "serde", feature = "codec"))]
 macro_rules! from_low_u64_be {
     ($hash: ident, $val: expr) => {{
diff --git a/rust-toolchain b/rust-toolchain
index 71b64c1..0a7fdc0 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-nightly-2019-03-05
\ No newline at end of file
+nightly-2019-04-17
\ No newline at end of file
diff --git a/ustd/src/lib.rs b/ustd/src/lib.rs
index 31c584b..caf7025 100644
--- a/ustd/src/lib.rs
+++ b/ustd/src/lib.rs
@@ -21,7 +21,7 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(not(feature = "std"), feature(core_intrinsics))]
-#![cfg_attr(not(feature = "std"), feature(alloc))]
+#![cfg_attr(not(feature = "std"), feature(alloc_prelude))]
 
 use cfg_if::cfg_if;
 
@@ -32,7 +32,7 @@ cfg_if! {
         pub use alloc::boxed;
         pub use alloc::collections;
         pub use alloc::fmt as alloc_fmt;
-        pub use alloc::prelude as alloc_prelude;
+        pub use alloc::prelude::v1 as alloc_prelude;
         pub use alloc::rc;
         pub use alloc::string;
         pub use alloc::vec;