diff --git a/rust-version b/rust-version
index cbd8e33577..e278a80633 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-24a9bcbb7cb0d8bdc11b8252a9c13f7562c7e4ca
+481068a707679257e2a738b40987246e0420e787
diff --git a/src/eval.rs b/src/eval.rs
index b29ce35377..6132c50253 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -1,3 +1,5 @@
+//! Main evaluator loop and setting up the initial stack frame.
+
 use rand::rngs::StdRng;
 use rand::SeedableRng;
 
@@ -29,23 +31,22 @@ pub fn create_ecx<'mir, 'tcx: 'mir>(
     main_id: DefId,
     config: MiriConfig,
 ) -> InterpResult<'tcx, InterpCx<'mir, 'tcx, Evaluator<'tcx>>> {
-    let mut ecx = InterpCx::new(
-        tcx.at(syntax::source_map::DUMMY_SP),
-        ty::ParamEnv::reveal_all(),
-        Evaluator::new(),
-    );
 
     // FIXME(https://github.com/rust-lang/miri/pull/803): no validation on Windows.
-    let target_os = ecx.tcx.tcx.sess.target.target.target_os.to_lowercase();
+    let target_os = tcx.sess.target.target.target_os.to_lowercase();
     let validate = if target_os == "windows" {
         false
     } else {
         config.validate
     };
 
-    // FIXME: InterpCx::new should take an initial MemoryExtra
-    ecx.memory_mut().extra = MemoryExtra::new(config.seed.map(StdRng::seed_from_u64), validate);
-    
+    let mut ecx = InterpCx::new(
+        tcx.at(syntax::source_map::DUMMY_SP),
+        ty::ParamEnv::reveal_all(),
+        Evaluator::new(),
+        MemoryExtra::new(config.seed.map(StdRng::seed_from_u64), validate),
+    );
+
     let main_instance = ty::Instance::mono(ecx.tcx.tcx, main_id);
     let main_mir = ecx.load_mir(main_instance.def)?;
 
diff --git a/src/machine.rs b/src/machine.rs
index 930eeee96b..0875331131 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -1,3 +1,6 @@
+//! Global machine state as well as implementation of the interpreter engine
+//! `Machine` trait.
+
 use std::rc::Rc;
 use std::borrow::Cow;
 use std::collections::HashMap;
@@ -48,7 +51,7 @@ pub struct AllocExtra {
 }
 
 /// Extra global memory data
-#[derive(Default, Clone, Debug)]
+#[derive(Clone, Debug)]
 pub struct MemoryExtra {
     pub stacked_borrows: stacked_borrows::MemoryExtra,
     pub intptrcast: intptrcast::MemoryExtra,
diff --git a/src/range_map.rs b/src/range_map.rs
index 16e7e27241..aa9a87887d 100644
--- a/src/range_map.rs
+++ b/src/range_map.rs
@@ -1,5 +1,3 @@
-#![allow(unused)]
-
 //! Implements a map from integer indices to data.
 //! Rather than storing data for every index, internally, this maps entire ranges to the data.
 //! To this end, the APIs all work on ranges, not on individual integers. Ranges are split as
@@ -8,7 +6,6 @@
 //! via the iteration APIs.
 
 use std::ops;
-use std::num::NonZeroU64;
 
 use rustc::ty::layout::Size;
 
@@ -158,7 +155,7 @@ impl<T> RangeMap<T> {
                 let mut end_idx = first_idx; // when the loop is done, this is the first excluded element.
                 loop {
                     // Compute if `end` is the last element we need to look at.
-                    let done = (self.v[end_idx].range.end >= offset+len);
+                    let done = self.v[end_idx].range.end >= offset+len;
                     // We definitely need to include `end`, so move the index.
                     end_idx += 1;
                     debug_assert!(done || end_idx < self.v.len(), "iter_mut: end-offset {} is out-of-bounds", offset+len);
@@ -284,7 +281,7 @@ mod tests {
             .map(|&t| t).collect::<Vec<_>>(), vec![19, 19]);
 
         // A NOP `iter_mut` should trigger merging.
-        for x in map.iter_mut(Size::from_bytes(15), Size::from_bytes(5)) { }
+        for _ in map.iter_mut(Size::from_bytes(15), Size::from_bytes(5)) { }
         assert_eq!(map.v.len(), 5);
         assert_eq!(
             to_vec(&map, 10, 10),
diff --git a/src/shims/tls.rs b/src/shims/tls.rs
index 9a22c03bf2..e2f2dab518 100644
--- a/src/shims/tls.rs
+++ b/src/shims/tls.rs
@@ -1,3 +1,5 @@
+//! Implement thread-local storage.
+
 use std::collections::BTreeMap;
 
 use rustc_target::abi::LayoutOf;
diff --git a/src/stacked_borrows.rs b/src/stacked_borrows.rs
index 5c59066c47..acd1aec5b7 100644
--- a/src/stacked_borrows.rs
+++ b/src/stacked_borrows.rs
@@ -1,3 +1,6 @@
+//! Implements "Stacked Borrows".  See <https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md>
+//! for further information.
+
 use std::cell::RefCell;
 use std::collections::{HashMap, HashSet};
 use std::rc::Rc;
diff --git a/tests/run-pass/move-undef-primval.rs b/tests/run-pass/move-undef-primval.rs
index 73c33943a6..b8bd869b48 100644
--- a/tests/run-pass/move-undef-primval.rs
+++ b/tests/run-pass/move-undef-primval.rs
@@ -1,3 +1,5 @@
+#![allow(deprecated)]
+
 struct Foo {
     _inner: i32,
 }