diff --git a/src/account.rs b/src/account.rs
index 037e21965..03b5463ab 100644
--- a/src/account.rs
+++ b/src/account.rs
@@ -10,6 +10,7 @@ use util::uint::*;
 pub const SHA3_EMPTY: H256 = H256( [0xc5, 0xd2, 0x46, 0x01, 0x86, 0xf7, 0x23, 0x3c, 0x92, 0x7e, 0x7d, 0xb2, 0xdc, 0xc7, 0x03, 0xc0, 0xe5, 0x00, 0xb6, 0x53, 0xca, 0x82, 0x27, 0x3b, 0x7b, 0xfa, 0xd8, 0x04, 0x5d, 0x85, 0xa4, 0x70] );
 
 /// Single account in the system.
+#[derive(Debug)]
 pub struct Account {
 	// Balance of the account.
 	balance: U256,
@@ -95,8 +96,8 @@ impl Account {
 			_ => {}
 		}
 		// fetch - cannot be done in match because of the borrow rules.
-		let t = TrieDB::new_existing(db, &mut self.storage_root);
-		let r = H256::from_slice(t.at(key.bytes()).unwrap_or(&[0u8;32][..]));
+		let t = TrieDBMut::new_existing(db, &mut self.storage_root);
+		let r = H256::from_slice(t.get(key.bytes()).unwrap_or(&[0u8;32][..]));
 		self.storage_overlay.insert(key, r.clone());
 		r
 	}
@@ -140,7 +141,7 @@ impl Account {
 	}
 
 	/// Provide a database to lookup `code_hash`. Should not be called if it is a contract without code.
-	pub fn ensure_cached(&mut self, db: &HashDB) -> bool {
+	pub fn cache_code(&mut self, db: &HashDB) -> bool {
 		// TODO: fill out self.code_cache;
 /*		return !self.is_cached() ||
 			match db.lookup(&self.code_hash.unwrap()) {	// why doesn't this work? unwrap causes move?!
@@ -176,7 +177,7 @@ impl Account {
 
 	/// Commit the `storage_overlay` to the backing DB and update `storage_root`.
 	pub fn commit_storage(&mut self, db: &mut HashDB) {
-		let mut t = TrieDB::new(db, &mut self.storage_root);
+		let mut t = TrieDBMut::new(db, &mut self.storage_root);
 		for (k, v) in self.storage_overlay.iter() {
 			// cast key and value to trait type,
 			// so we can call overloaded `to_bytes` method
@@ -247,7 +248,7 @@ fn note_code() {
 	};
 
 	let mut a = Account::from_rlp(&rlp);
-	assert_eq!(a.ensure_cached(&db), true);
+	assert_eq!(a.cache_code(&db), true);
 
 	let mut a = Account::from_rlp(&rlp);
 	assert_eq!(a.note_code(vec![0x55, 0x44, 0xffu8]), Ok(()));
diff --git a/src/blockheader.rs b/src/blockheader.rs
index b79b57815..2681c55e7 100644
--- a/src/blockheader.rs
+++ b/src/blockheader.rs
@@ -109,6 +109,4 @@ impl Encodable for Header {
 
 #[cfg(test)]
 mod tests {
-	fn encoding_and_decoding() {
-	}
 }
diff --git a/src/state.rs b/src/state.rs
index 5674035bf..978b55fbf 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -5,7 +5,31 @@ use util::overlaydb::*;
 use util::trie::*;
 use util::rlp::*;
 use util::uint::*;
+use std::mem;
+//use std::cell::*;
+//use std::ops::*;
 use account::Account;
+/*
+enum ValueOrRef<'self, 'db: 'self> {
+	Value(OverlayDB),
+	Ref(&'db mut OverlayDB)
+}
+
+impl<'self, 'db> ValueOrRef<'self, 'db: 'self> {
+	pub fn get_mut(&mut self) -> &mut OverlayDB {
+		match self {
+			Value(ref mut x) => x,
+			Ref(x) => x,
+		}
+	}
+	pub fn get(&self) -> &OverlayDB {
+		match self {
+			Value(ref x) => x,
+			Ref(x) => x,
+		}
+	}
+}
+*/
 
 /// Representation of the entire state of all accounts in the system.
 pub struct State {
@@ -22,7 +46,7 @@ impl State {
 		let mut root = H256::new();
 		{
 			// init trie and reset root too null
-			let _ = TrieDB::new(&mut db, &mut root);
+			let _ = TrieDBMut::new(&mut db, &mut root);
 		}
 
 		State {
@@ -37,7 +61,7 @@ impl State {
 	pub fn new_existing(mut db: OverlayDB, mut root: H256, account_start_nonce: U256) -> State {
 		{
 			// trie should panic! if root does not exist
-			let _ = TrieDB::new_existing(&mut db, &mut root);
+			let _ = TrieDBMut::new_existing(&mut db, &mut root);
 		}
 
 		State {
@@ -58,12 +82,50 @@ impl State {
 		&self.root
 	}
 
+	/// Desttroy the current database and return it.
+	/// WARNING: the struct should be dropped immediately following this.
+	pub fn take_db(&mut self) -> OverlayDB {
+		mem::replace(&mut self.db, OverlayDB::new_temp())
+	}
+
+	/// Destroy the current object and return root and database.
+	pub fn drop(mut self) -> (H256, OverlayDB) {
+		(mem::replace(&mut self.root, H256::new()), mem::replace(&mut self.db, OverlayDB::new_temp()))
+	}
+
 	/// Expose the underlying database; good to use for calling `state.db().commit()`.
 	pub fn db(&mut self) -> &mut OverlayDB {
 		&mut self.db
 	}
 
-	/// Commit accounts to TrieDB. This is similar to cpp-ethereum's dev::eth::commit.
+	/// Get the balance of account `a`.
+	// TODO: make immutable
+	pub fn balance(&mut self, a: &Address) -> U256 {
+		self.get(a, false).as_ref().map(|account| account.balance().clone()).unwrap_or(U256::from(0u8))
+	}
+
+	/// Add `incr` to the balance of account `a`.
+	pub fn add_balance(&mut self, a: &Address, incr: &U256) {
+		self.require(a, false).add_balance(incr)
+	}
+
+	/// Subtract `decr` from the balance of account `a`.
+	pub fn sub_balance(&mut self, a: &Address, decr: &U256) {
+		self.require(a, false).sub_balance(decr)
+	}
+
+	/// Get the nonce of account `a`.
+	// TODO: make immutable
+	pub fn nonce(&mut self, a: &Address) -> U256 {
+		self.get(a, false).as_ref().map(|account| account.nonce().clone()).unwrap_or(U256::from(0u8))
+	}
+
+	/// Increment the nonce of account `a` by 1.
+	pub fn inc_nonce(&mut self, a: &Address) {
+		self.require(a, false).inc_nonce()
+	}
+
+	/// Commit accounts to TrieDBMut. This is similar to cpp-ethereum's dev::eth::commit.
 	/// `accounts` is mutable because we may need to commit the code or storage and record that.
 	pub fn commit_into(db: &mut HashDB, mut root: H256, accounts: &mut HashMap<Address, Option<Account>>) -> H256 {
 		// first, commit the sub trees.
@@ -79,7 +141,7 @@ impl State {
 		}
 
 		{
-			let mut trie = TrieDB::new_existing(db, &mut root);
+			let mut trie = TrieDBMut::new_existing(db, &mut root);
 			for (address, ref a) in accounts.iter() {
 				match a {
 					&&Some(ref account) => trie.insert(address, &account.rlp()),
@@ -98,23 +160,42 @@ impl State {
 
 	/// Pull account `a` in our cache from the trie DB. `require_code` requires that the code be cached, too.
 	/// `force_create` creates a new, empty basic account if there is not currently an active account.
-	fn ensure_cached(&mut self, a: &Address, require_code: bool, force_create: bool) {
+	// TODO: make immutable.
+	fn get(&mut self, a: &Address, require_code: bool) -> Option<&Account> {
 		if self.cache.get(a).is_none() {
 			// load from trie.
-			self.cache.insert(a.clone(), TrieDB::new(&mut self.db, &mut self.root).at(&a).map(|rlp| Account::from_rlp(rlp)));
+			let t = TrieDBMut::new_existing(&mut self.db, &mut self.root);
+			self.cache.insert(a.clone(), t.get(&a).map(|rlp| { println!("RLP: {:?}", rlp); Account::from_rlp(rlp) }));
+		}
+
+		let db = &self.db;
+		self.cache.get_mut(a).unwrap().as_mut().map(|account| {
+			if require_code {
+				account.cache_code(db);
+			}
+			account as &Account
+		})
+	}
+
+	/// Pull account `a` in our cache from the trie DB. `require_code` requires that the code be cached, too.
+	/// `force_create` creates a new, empty basic account if there is not currently an active account.
+	fn require(&mut self, a: &Address, require_code: bool) -> &mut Account {
+		if self.cache.get(a).is_none() {
+			// load from trie.
+			self.cache.insert(a.clone(), TrieDBMut::new(&mut self.db, &mut self.root).get(&a).map(|rlp| Account::from_rlp(rlp)));
 		}
 
 		if self.cache.get(a).unwrap().is_none() {
-			if !force_create { return; }
-			// create a new account
 			self.cache.insert(a.clone(), Some(Account::new_basic(U256::from(0u8))));
 		}
 
-		if require_code {
-			if let &mut Some(ref mut account) = self.cache.get_mut(a).unwrap() {
-				account.ensure_cached(&self.db);
+		let db = &self.db;
+		self.cache.get_mut(a).unwrap().as_mut().map(|account| {
+			if require_code {
+				account.cache_code(db);
 			}
-		}
+			account
+		}).unwrap()
 	}
 }
 
@@ -125,17 +206,72 @@ use super::*;
 use util::hash::*;
 use util::trie::*;
 use util::rlp::*;
+use util::uint::*;
 use std::str::FromStr;
 
 #[test]
-fn playpen() {
+fn get_from_database() {
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	let (r, db) = {
+		let mut s = State::new_temp();
+		s.inc_nonce(&a);
+		s.add_balance(&a, &U256::from(69u64));
+		s.commit();
+		assert_eq!(s.balance(&a), U256::from(69u64));
+		(s.root().clone(), s.take_db())
+	};
+
+	let mut s = State::new_existing(db, r, U256::from(0u8));
+	assert_eq!(s.balance(&a), U256::from(69u64));
+	assert_eq!(s.nonce(&a), U256::from(1u64));
+}
+
+#[test]
+fn alter_balance() {
+	let mut s = State::new_temp();
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	s.add_balance(&a, &U256::from(69u64));
+	assert_eq!(s.balance(&a), U256::from(69u64));
+	s.commit();
+	assert_eq!(s.balance(&a), U256::from(69u64));
+	s.sub_balance(&a, &U256::from(42u64));
+	assert_eq!(s.balance(&a), U256::from(27u64));
+	s.commit();
+	assert_eq!(s.balance(&a), U256::from(27u64));
+}
+
+#[test]
+fn alter_nonce() {
+	let mut s = State::new_temp();
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	s.inc_nonce(&a);
+	assert_eq!(s.nonce(&a), U256::from(1u64));
+	s.inc_nonce(&a);
+	assert_eq!(s.nonce(&a), U256::from(2u64));
+	s.commit();
+	assert_eq!(s.nonce(&a), U256::from(2u64));
+	s.inc_nonce(&a);
+	assert_eq!(s.nonce(&a), U256::from(3u64));
+	s.commit();
+	assert_eq!(s.nonce(&a), U256::from(3u64));
+}
+
+#[test]
+fn balance_nonce() {
+	let mut s = State::new_temp();
+	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
+	assert_eq!(s.balance(&a), U256::from(0u64));
+	assert_eq!(s.nonce(&a), U256::from(0u64));
+	s.commit();
+	assert_eq!(s.balance(&a), U256::from(0u64));
+	assert_eq!(s.nonce(&a), U256::from(0u64));
 }
 
 #[test]
 fn ensure_cached() {
 	let mut s = State::new_temp();
 	let a = Address::from_str("0000000000000000000000000000000000000000").unwrap();
-	s.ensure_cached(&a, false, true);
+	s.require(&a, false);
 	s.commit();
 	assert_eq!(s.root().hex(), "ec68b85fa2e0526dc0e821a5b33135459114f19173ce0479f5c09b21cc25b9a4");
 }