diff --git a/util/bigint/src/uint.rs b/util/bigint/src/uint.rs
index f87b494a9..5c8da4a3c 100644
--- a/util/bigint/src/uint.rs
+++ b/util/bigint/src/uint.rs
@@ -92,8 +92,8 @@ macro_rules! uint_overflowing_add_reg {
 macro_rules! uint_overflowing_add {
 	(U256, $n_words: expr, $self_expr: expr, $other: expr) => ({
 		let mut result: [u64; 4] = unsafe { mem::uninitialized() };
-		let self_t: &[u64; 4] = unsafe { &mem::transmute($self_expr) };
-		let other_t: &[u64; 4] = unsafe { &mem::transmute($other) };
+		let self_t: &[u64; 4] = &self.0;
+		let other_t: &[u64; 4] = &other.0;
 
 		let overflow: u8;
 		unsafe {
@@ -115,8 +115,8 @@ macro_rules! uint_overflowing_add {
 	});
 	(U512, $n_words: expr, $self_expr: expr, $other: expr) => ({
 		let mut result: [u64; 8] = unsafe { mem::uninitialized() };
-		let self_t: &[u64; 8] = unsafe { &mem::transmute($self_expr) };
-		let other_t: &[u64; 8] = unsafe { &mem::transmute($other) };
+		let self_t: &[u64; 8] = &self.0;
+		let other_t: &[u64; 8] = &other.0;
 
 		let overflow: u8;
 
@@ -196,8 +196,8 @@ macro_rules! uint_overflowing_sub_reg {
 macro_rules! uint_overflowing_sub {
 	(U256, $n_words: expr, $self_expr: expr, $other: expr) => ({
 		let mut result: [u64; 4] = unsafe { mem::uninitialized() };
-		let self_t: &[u64; 4] = unsafe { &mem::transmute($self_expr) };
-		let other_t: &[u64; 4] = unsafe { &mem::transmute($other) };
+		let self_t: &[u64; 4] = &self.0;
+		let other_t: &[u64; 4] = &other.0;
 
 		let overflow: u8;
 		unsafe {
@@ -218,8 +218,8 @@ macro_rules! uint_overflowing_sub {
 	});
 	(U512, $n_words: expr, $self_expr: expr, $other: expr) => ({
 		let mut result: [u64; 8] = unsafe { mem::uninitialized() };
-		let self_t: &[u64; 8] = unsafe { &mem::transmute($self_expr) };
-		let other_t: &[u64; 8] = unsafe { &mem::transmute($other) };
+		let self_t: &[u64; 8] = &self.0;
+		let other_t: &[u64; 8] = &other.0;
 
 		let overflow: u8;
 
@@ -270,8 +270,8 @@ macro_rules! uint_overflowing_sub {
 macro_rules! uint_overflowing_mul {
 	(U256, $n_words: expr, $self_expr: expr, $other: expr) => ({
 		let mut result: [u64; 4] = unsafe { mem::uninitialized() };
-		let self_t: &[u64; 4] = unsafe { &mem::transmute($self_expr) };
-		let other_t: &[u64; 4] = unsafe { &mem::transmute($other) };
+		let self_t: &[u64; 4] = &self.0;
+		let other_t: &[u64; 4] = &self.0;
 
 		let overflow: u64;
 		unsafe {
@@ -548,6 +548,7 @@ pub trait Uint: Sized + Default + FromStr + From<u64> + fmt::Debug + fmt::Displa
 macro_rules! construct_uint {
 	($name:ident, $n_words:expr) => (
 		/// Little-endian large integer type
+		#[repr(C)]
 		#[derive(Copy, Clone, Eq, PartialEq)]
 		pub struct $name(pub [u64; $n_words]);
 
@@ -1132,8 +1133,8 @@ impl U256 {
 	/// No overflow possible
 	#[cfg(all(asm_available, target_arch="x86_64"))]
 	pub fn full_mul(self, other: U256) -> U512 {
-		let self_t: &[u64; 4] = unsafe { &mem::transmute(self) };
-		let other_t: &[u64; 4] = unsafe { &mem::transmute(other) };
+		let self_t: &[u64; 4] = &self.0;
+		let other_t: &[u64; 4] = &other.0;
 		let mut result: [u64; 8] = unsafe { mem::uninitialized() };
 		unsafe {
 			asm!("