diff --git a/hashdb/Cargo.toml b/hashdb/Cargo.toml
index f5e63fb..37b175f 100644
--- a/hashdb/Cargo.toml
+++ b/hashdb/Cargo.toml
@@ -6,5 +6,4 @@ description = "trait for hash-keyed databases."
 license = "GPL-3.0"
 
 [dependencies]
-elastic-array = "0.10"
-heapsize = "0.4"
\ No newline at end of file
+elastic-array = "0.10"
\ No newline at end of file
diff --git a/hashdb/src/lib.rs b/hashdb/src/lib.rs
index 4f5bed4..a404b4f 100644
--- a/hashdb/src/lib.rs
+++ b/hashdb/src/lib.rs
@@ -16,10 +16,8 @@
 
 //! Database of byte-slices keyed to their hash.
 extern crate elastic_array;
-extern crate heapsize;
 
 use elastic_array::ElasticArray128;
-use heapsize::HeapSizeOf;
 use std::collections::HashMap;
 use std::{fmt::Debug, hash::Hash};
 
@@ -28,7 +26,7 @@ use std::{fmt::Debug, hash::Hash};
 /// `Out` associated type with the necessary bounds.
 pub trait Hasher: Sync + Send {
 	/// The output type of the `Hasher`
-	type Out: AsRef<[u8]> + AsMut<[u8]> + Default + HeapSizeOf + Debug + PartialEq + Eq + Hash + Send + Sync + Clone + Copy;
+	type Out: AsRef<[u8]> + AsMut<[u8]> + Default + Debug + PartialEq + Eq + Hash + Send + Sync + Clone + Copy;
 	/// What to use to build `HashMap`s with this `Hasher`
 	type StdHasher: Sync + Send + Default + std::hash::Hasher;
 	/// The length in bytes of the `Hasher` output
diff --git a/memorydb/src/lib.rs b/memorydb/src/lib.rs
index d49ce9d..f07bce8 100644
--- a/memorydb/src/lib.rs
+++ b/memorydb/src/lib.rs
@@ -87,11 +87,11 @@ pub struct MemoryDB<H: KeyHasher> {
 	hashed_null_node: H::Out,
 }
 
-impl<H: KeyHasher> Default for MemoryDB<H> {
+impl<H> Default for MemoryDB<H>  where H: KeyHasher, H::Out: HeapSizeOf {
 	fn default() -> Self { Self::new() }
 }
 
-impl<H: KeyHasher> MemoryDB<H> {
+impl<H> MemoryDB<H> where H: KeyHasher, H::Out: HeapSizeOf {
 	/// Create a new instance of the memory DB.
 	pub fn new() -> MemoryDB<H> {
 		MemoryDB {
diff --git a/patricia_trie/Cargo.toml b/patricia_trie/Cargo.toml
index be80eae..2d08e8b 100644
--- a/patricia_trie/Cargo.toml
+++ b/patricia_trie/Cargo.toml
@@ -7,11 +7,10 @@ license = "GPL-3.0"
 
 [dependencies]
 elastic-array = "0.10"
-heapsize = "0.4"
 log = "0.3"
 rand = "0.4"
-hashdb = { version = "0.2.0", path = "../hashdb" }
-parity-bytes = { version = "0.1.0", path = "../parity-bytes" }
+hashdb = { version = "0.2", path = "../hashdb" }
+parity-bytes = { version = "0.1", path = "../parity-bytes" }
 
 [dev-dependencies]
 env_logger = "0.5"
diff --git a/patricia_trie/src/lib.rs b/patricia_trie/src/lib.rs
index 36d6167..b09685d 100644
--- a/patricia_trie/src/lib.rs
+++ b/patricia_trie/src/lib.rs
@@ -18,7 +18,6 @@
 extern crate elastic_array;
 extern crate parity_bytes as bytes; // TODO: name changed; update upstream when `parity-common` is available
 extern crate hashdb;
-extern crate heapsize;
 extern crate rand;
 #[macro_use]
 extern crate log;
diff --git a/patricia_trie/src/triedbmut.rs b/patricia_trie/src/triedbmut.rs
index 51005e9..fc6c3e4 100644
--- a/patricia_trie/src/triedbmut.rs
+++ b/patricia_trie/src/triedbmut.rs
@@ -31,7 +31,6 @@ use std::collections::{HashSet, VecDeque};
 use std::marker::PhantomData;
 use std::mem;
 use std::ops::Index;
-use heapsize::HeapSizeOf;
 use std::{fmt::Debug, hash::Hash};
 
 // For lookups into the Node storage buffer.
@@ -79,7 +78,7 @@ enum Node<H> {
 	Branch(Box<[Option<NodeHandle<H>>; 16]>, Option<DBValue>)
 }
 
-impl<O> Node<O> where O: AsRef<[u8]> + AsMut<[u8]> + Default + HeapSizeOf + Debug + PartialEq + Eq + Hash + Send + Sync + Clone + Copy {
+impl<O> Node<O> where O: AsRef<[u8]> + AsMut<[u8]> + Default + Debug + PartialEq + Eq + Hash + Send + Sync + Clone + Copy {
 	// load an inline node into memory or get the hash to do the lookup later.
 	fn inline_or_hash<C, H>(node: &[u8], db: &HashDB<H>, storage: &mut NodeStorage<H::Out>) -> NodeHandle<H::Out>
 	where C: NodeCodec<H>,