diff --git a/Cargo.toml b/Cargo.toml
index 55fb2440..933e6930 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,7 @@ git = "https://github.com/apoelstra/bitcoin-secp256k1-rs.git"
 
 [dependencies]
 byteorder = "*"
+num_cpus = "*"
 rand = "*"
 rust-crypto = "*"
 rustc-serialize = "*"
diff --git a/src/blockdata/blockchain.rs b/src/blockdata/blockchain.rs
index b7d02a89..cbeacb46 100644
--- a/src/blockdata/blockchain.rs
+++ b/src/blockdata/blockchain.rs
@@ -23,7 +23,7 @@
 //!
 
 use std::num::Zero;
-use std::kinds::marker;
+use std::marker;
 
 use blockdata::block::{Block, BlockHeader};
 use blockdata::transaction::Transaction;
diff --git a/src/blockdata/utxoset.rs b/src/blockdata/utxoset.rs
index 93c3b5d4..4966c0d7 100644
--- a/src/blockdata/utxoset.rs
+++ b/src/blockdata/utxoset.rs
@@ -20,10 +20,10 @@
 
 use std::cmp;
 use std::collections::HashMap;
-use std::collections::hashmap::Entries;
+use std::collections::hash::map::Iter;
 use std::default::Default;
 use std::mem;
-use std::os::num_cpus;
+use num_cpus;
 use std::sync::Future;
 
 use blockdata::transaction::{Transaction, TxOut};
@@ -69,7 +69,7 @@ impl_consensus_encoding!(UtxoNode, height, outputs);
 
 /// An iterator over UTXOs
 pub struct UtxoIterator<'a> {
-  tx_iter: Entries<'a, Sha256dHash, UtxoNode>,
+  tx_iter: Iter<'a, Sha256dHash, UtxoNode>,
   current_key: Sha256dHash,
   current: Option<&'a UtxoNode>,
   tx_index: u32
@@ -261,7 +261,7 @@ impl UtxoSet {
       let mut future_vec = Vec::with_capacity(block.txdata.len() - 1);
       // skip the genesis since we don't validate this script. (TODO this might
       // be a consensus bug since we don't even check that the opcodes make sense.)
-      let n_threads = cmp::min(block.txdata.len() - 1, num_cpus());
+      let n_threads = cmp::min(block.txdata.len() - 1, num_cpus::get());
       for j in range(0, n_threads) {
         let n_elems = block.txdata.len() - 1;
         let start = 1 + j * n_elems / n_threads;
diff --git a/src/lib.rs b/src/lib.rs
index f13975fa..ab4e1a7a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -46,6 +46,7 @@ extern crate alloc;
 extern crate byteorder;
 extern crate collections;
 extern crate core;
+extern crate num_cpus;
 extern crate rand;
 extern crate rustc_serialize as serialize;
 extern crate test;
diff --git a/src/util/patricia_tree.rs b/src/util/patricia_tree.rs
index 9c0ef214..16e270c9 100644
--- a/src/util/patricia_tree.rs
+++ b/src/util/patricia_tree.rs
@@ -22,7 +22,7 @@
 
 use core::fmt::Debug;
 use core::cmp;
-use std::kinds::marker;
+use std::marker;
 use std::num::{Zero, One};
 
 use network::encodable::{ConsensusDecodable, ConsensusEncodable};
diff --git a/src/util/thinvec.rs b/src/util/thinvec.rs
index 7c671c5a..d3afa128 100644
--- a/src/util/thinvec.rs
+++ b/src/util/thinvec.rs
@@ -21,7 +21,7 @@
 
 use alloc::heap::{allocate, reallocate, deallocate};
 use std::raw;
-use std::slice::{Iter, MutIter};
+use std::slice::{Iter, IterMut};
 use std::{fmt, mem, ptr};
 use std::u32;
 
@@ -69,7 +69,7 @@ impl<T> ThinVec<T> {
 
   /// Mutable iterator over elements of the vector
   #[inline]
-  pub fn iter_mut<'a>(&'a mut self) -> MutIter<'a, T> {
+  pub fn iter_mut<'a>(&'a mut self) -> IterMut<'a, T> {
     self.as_mut_slice().iter_mut()
   }