diff --git a/src/libcollections/slice.rs b/src/libcollections/slice.rs
index 4599aff000d..29301bfd6fe 100644
--- a/src/libcollections/slice.rs
+++ b/src/libcollections/slice.rs
@@ -1123,7 +1123,7 @@ impl Iterator for ElementSwaps {
     // #[inline]
     fn next(&mut self) -> Option<(usize, usize)> {
         fn new_pos_wrapping(i: usize, s: Direction) -> usize {
-            i.wrapping_add(match s { Pos => 1, Neg => -1 })
+            i.wrapping_add(match s { Pos => 1, Neg => !0 /* aka -1 */ })
         }
 
         fn new_pos(i: usize, s: Direction) -> usize {
diff --git a/src/libcore/atomic.rs b/src/libcore/atomic.rs
index 8c396a4e7fb..d738ff947c4 100644
--- a/src/libcore/atomic.rs
+++ b/src/libcore/atomic.rs
@@ -161,7 +161,7 @@ pub enum Ordering {
         AtomicUsize { v: UnsafeCell { value: 0, } };
 
 // NB: Needs to be -1 (0b11111111...) to make fetch_nand work correctly
-const UINT_TRUE: usize = -1;
+const UINT_TRUE: usize = !0;
 
 impl AtomicBool {
     /// Creates a new `AtomicBool`.
diff --git a/src/libcore/cell.rs b/src/libcore/cell.rs
index 906c87f3ffd..76e09eedbdf 100644
--- a/src/libcore/cell.rs
+++ b/src/libcore/cell.rs
@@ -287,7 +287,7 @@ pub enum BorrowState {
 // (will not outgrow its range since `usize` is the size of the address space)
 type BorrowFlag = usize;
 const UNUSED: BorrowFlag = 0;
-const WRITING: BorrowFlag = -1;
+const WRITING: BorrowFlag = !0;
 
 impl<T> RefCell<T> {
     /// Creates a new `RefCell` containing `value`.
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index a4829ed96b3..13f168b3fdb 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -517,7 +517,7 @@ fn one() -> $T { 1 }
             fn min_value() -> $T { 0 }
 
             #[inline]
-            fn max_value() -> $T { -1 }
+            fn max_value() -> $T { !0 }
 
             #[inline]
             fn count_ones(self) -> u32 {
diff --git a/src/libcore/ops.rs b/src/libcore/ops.rs
index 862eb16d0bf..e1a9efd69ad 100644
--- a/src/libcore/ops.rs
+++ b/src/libcore/ops.rs
@@ -482,8 +482,10 @@ pub trait Neg {
     fn neg(self) -> Self::Output;
 }
 
-macro_rules! neg_impl {
-    ($($t:ty)*) => ($(
+
+
+macro_rules! neg_impl_core {
+    ($id:ident => $body:expr, $($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
         #[allow(unsigned_negation)]
         impl Neg for $t {
@@ -492,14 +494,28 @@ impl Neg for $t {
 
             #[inline]
             #[stable(feature = "rust1", since = "1.0.0")]
-            fn neg(self) -> $t { -self }
+            fn neg(self) -> $t { let $id = self; $body }
         }
 
         forward_ref_unop! { impl Neg, neg for $t }
     )*)
 }
 
-neg_impl! { usize u8 u16 u32 u64 isize i8 i16 i32 i64 f32 f64 }
+macro_rules! neg_impl_numeric {
+    ($($t:ty)*) => { neg_impl_core!{ x => -x, $($t)*} }
+}
+
+macro_rules! neg_impl_unsigned {
+    ($($t:ty)*) => {
+        neg_impl_core!{ x => {
+            #[cfg(stage0)]
+            use ::num::wrapping::WrappingOps;
+            !x.wrapping_add(1)
+        }, $($t)*} }
+}
+
+neg_impl_unsigned! { usize u8 u16 u32 u64 }
+neg_impl_numeric! { isize i8 i16 i32 i64 f32 f64 }
 
 /// The `Not` trait is used to specify the functionality of unary `!`.
 ///
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index 934c4515614..c78fa803361 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -873,7 +873,7 @@ fn next(&mut self, haystack: &[u8], needle: &[u8], long_period: bool)
     #[allow(dead_code)]
     #[allow(deprecated)]
     fn maximal_suffix(arr: &[u8], reversed: bool) -> (usize, usize) {
-        let mut left: usize = -1; // Corresponds to i in the paper
+        let mut left: usize = !0; // Corresponds to i in the paper
         let mut right = 0; // Corresponds to j in the paper
         let mut offset = 1; // Corresponds to k in the paper
         let mut period = 1; // Corresponds to p in the paper
diff --git a/src/liblibc/lib.rs b/src/liblibc/lib.rs
index b7162c4a177..77e18be298b 100644
--- a/src/liblibc/lib.rs
+++ b/src/liblibc/lib.rs
@@ -4696,7 +4696,7 @@ pub mod posix88 {
             pub const MAP_FIXED : c_int = 0x0010;
             pub const MAP_ANON : c_int = 0x1000;
 
-            pub const MAP_FAILED : *mut c_void = -1 as *mut c_void;
+            pub const MAP_FAILED : *mut c_void = !0 as *mut c_void;
 
             pub const MCL_CURRENT : c_int = 0x0001;
             pub const MCL_FUTURE : c_int = 0x0002;
diff --git a/src/libstd/rt/mod.rs b/src/libstd/rt/mod.rs
index 696c7960c3e..7ea77a79619 100644
--- a/src/libstd/rt/mod.rs
+++ b/src/libstd/rt/mod.rs
@@ -117,7 +117,7 @@ fn lang_start(main: *const u8, argc: isize, argv: *const *const u8) -> isize {
             use libc;
             use libc::funcs::posix01::signal::signal;
             unsafe {
-                assert!(signal(libc::SIGPIPE, libc::SIG_IGN) != -1);
+                assert!(signal(libc::SIGPIPE, libc::SIG_IGN) != !0);
             }
         }
         ignore_sigpipe();