diff --git a/src/bytes.rs b/src/bytes.rs
index 8d33a4108..98ab4c2d7 100644
--- a/src/bytes.rs
+++ b/src/bytes.rs
@@ -305,7 +305,11 @@ macro_rules! impl_uint_from_bytes {
 	($name: ident) => {
 		impl FromBytes for $name {
 			fn from_bytes(bytes: &[u8]) -> FromBytesResult<$name> {
-				Ok($name::from(bytes))
+				if bytes.len() <= $name::SIZE {
+					Ok($name::from(bytes))
+				} else {
+					Err(FromBytesError::DataIsTooLong)
+				}
 			}
 		}
 	}
diff --git a/src/lib.rs b/src/lib.rs
index de2cdbdf7..b856431cd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,5 @@
 #![feature(op_assign_traits)]
+#![feature(associated_consts)]
 //! Ethcore-util library
 //!
 //! ### Rust version:
diff --git a/src/uint.rs b/src/uint.rs
index 6fc8d19e1..b7411fd30 100644
--- a/src/uint.rs
+++ b/src/uint.rs
@@ -50,6 +50,8 @@ macro_rules! construct_uint {
 		pub struct $name(pub [u64; $n_words]);
 
 		impl $name {
+			pub const SIZE: usize = $n_words * 8;
+
 			/// Conversion to u32
 			#[inline]
 			pub fn low_u32(&self) -> u32 {