diff --git a/src/librustc/driver/session.rs b/src/librustc/driver/session.rs
index f752b68fea5fe..e497caa494604 100644
--- a/src/librustc/driver/session.rs
+++ b/src/librustc/driver/session.rs
@@ -28,7 +28,6 @@ use syntax::abi;
 use syntax::parse::token;
 use syntax;
 
-use std::int;
 use std::hashmap::{HashMap,HashSet};
 
 #[deriving(Clone)]
@@ -209,7 +208,7 @@ pub struct Session_ {
     building_library: @mut bool,
     working_dir: Path,
     lints: @mut HashMap<ast::NodeId, ~[(lint::lint, codemap::Span, ~str)]>,
-    node_id: @mut uint,
+    node_id: @mut ast::NodeId,
 }
 
 pub type Session = @Session_;
@@ -274,13 +273,15 @@ impl Session_ {
     pub fn next_node_id(&self) -> ast::NodeId {
         self.reserve_node_ids(1)
     }
-    pub fn reserve_node_ids(&self, count: uint) -> ast::NodeId {
+    pub fn reserve_node_ids(&self, count: ast::NodeId) -> ast::NodeId {
         let v = *self.node_id;
-        *self.node_id += count;
-        if v > (int::max_value as uint) {
-            self.bug("Input too large, ran out of node ids!");
+
+        match v.checked_add(&count) {
+            Some(next) => { *self.node_id = next; }
+            None => self.bug("Input too large, ran out of node ids!")
         }
-        v as int
+
+        v
     }
     pub fn diagnostic(&self) -> @mut diagnostic::span_handler {
         self.span_diagnostic
diff --git a/src/librustc/metadata/creader.rs b/src/librustc/metadata/creader.rs
index f7b1955191abd..e71db97628347 100644
--- a/src/librustc/metadata/creader.rs
+++ b/src/librustc/metadata/creader.rs
@@ -67,7 +67,7 @@ impl visit::Visitor<()> for ReadCrateVisitor {
 
 #[deriving(Clone)]
 struct cache_entry {
-    cnum: int,
+    cnum: ast::CrateNum,
     span: Span,
     hash: @str,
     metas: @~[@ast::MetaItem]
@@ -242,7 +242,7 @@ fn metas_with_ident(ident: @str, metas: ~[@ast::MetaItem])
 }
 
 fn existing_match(e: &Env, metas: &[@ast::MetaItem], hash: &str)
-               -> Option<int> {
+               -> Option<ast::CrateNum> {
     for c in e.crate_cache.iter() {
         if loader::metadata_matches(*c.metas, metas)
             && (hash.is_empty() || c.hash.as_slice() == hash) {
diff --git a/src/librustc/metadata/decoder.rs b/src/librustc/metadata/decoder.rs
index fbe3d7bbe9eea..ff53dda6f72f3 100644
--- a/src/librustc/metadata/decoder.rs
+++ b/src/librustc/metadata/decoder.rs
@@ -76,10 +76,10 @@ fn lookup_hash(d: ebml::Doc, eq_fn: |&[u8]| -> bool, hash: u64) ->
 
 pub type GetCrateDataCb<'self> = &'self fn(ast::CrateNum) -> Cmd;
 
-pub fn maybe_find_item(item_id: int, items: ebml::Doc) -> Option<ebml::Doc> {
-    fn eq_item(bytes: &[u8], item_id: int) -> bool {
+pub fn maybe_find_item(item_id: ast::NodeId, items: ebml::Doc) -> Option<ebml::Doc> {
+    fn eq_item(bytes: &[u8], item_id: ast::NodeId) -> bool {
         return u64_from_be_bytes(
-            bytes.slice(0u, 4u), 0u, 4u) as int
+            bytes.slice(0u, 4u), 0u, 4u) as ast::NodeId
             == item_id;
     }
     lookup_hash(items,
@@ -87,7 +87,7 @@ pub fn maybe_find_item(item_id: int, items: ebml::Doc) -> Option<ebml::Doc> {
                 (item_id as i64).hash())
 }
 
-fn find_item(item_id: int, items: ebml::Doc) -> ebml::Doc {
+fn find_item(item_id: ast::NodeId, items: ebml::Doc) -> ebml::Doc {
     match maybe_find_item(item_id, items) {
        None => fail!("lookup_item: id not found: {}", item_id),
        Some(d) => d
@@ -96,7 +96,7 @@ fn find_item(item_id: int, items: ebml::Doc) -> ebml::Doc {
 
 // Looks up an item in the given metadata and returns an ebml doc pointing
 // to the item data.
-pub fn lookup_item(item_id: int, data: @~[u8]) -> ebml::Doc {
+pub fn lookup_item(item_id: ast::NodeId, data: @~[u8]) -> ebml::Doc {
     let items = reader::get_doc(reader::Doc(data), tag_items);
     find_item(item_id, items)
 }
@@ -343,7 +343,7 @@ fn item_name(intr: @ident_interner, item: ebml::Doc) -> ast::Ident {
     let string = name.as_str_slice();
     match intr.find_equiv(&string) {
         None => token::str_to_ident(string),
-        Some(val) => ast::Ident::new(val),
+        Some(val) => ast::Ident::new(val as ast::Name),
     }
 }
 
diff --git a/src/librustc/metadata/tydecode.rs b/src/librustc/metadata/tydecode.rs
index 281998b081146..a595e50115bbc 100644
--- a/src/librustc/metadata/tydecode.rs
+++ b/src/librustc/metadata/tydecode.rs
@@ -58,7 +58,7 @@ type conv_did<'self> =
 
 pub struct PState<'self> {
     data: &'self [u8],
-    crate: int,
+    crate: ast::CrateNum,
     pos: uint,
     tcx: ty::ctxt
 }
@@ -101,7 +101,7 @@ fn parse_ident_(st: &mut PState, is_last: |char| -> bool) -> ast::Ident {
     return st.tcx.sess.ident_of(rslt);
 }
 
-pub fn parse_state_from_data<'a>(data: &'a [u8], crate_num: int,
+pub fn parse_state_from_data<'a>(data: &'a [u8], crate_num: ast::CrateNum,
                              pos: uint, tcx: ty::ctxt) -> PState<'a> {
     PState {
         data: data,
@@ -111,19 +111,19 @@ pub fn parse_state_from_data<'a>(data: &'a [u8], crate_num: int,
     }
 }
 
-pub fn parse_ty_data(data: &[u8], crate_num: int, pos: uint, tcx: ty::ctxt,
+pub fn parse_ty_data(data: &[u8], crate_num: ast::CrateNum, pos: uint, tcx: ty::ctxt,
                      conv: conv_did) -> ty::t {
     let mut st = parse_state_from_data(data, crate_num, pos, tcx);
     parse_ty(&mut st, conv)
 }
 
-pub fn parse_bare_fn_ty_data(data: &[u8], crate_num: int, pos: uint, tcx: ty::ctxt,
+pub fn parse_bare_fn_ty_data(data: &[u8], crate_num: ast::CrateNum, pos: uint, tcx: ty::ctxt,
                              conv: conv_did) -> ty::BareFnTy {
     let mut st = parse_state_from_data(data, crate_num, pos, tcx);
     parse_bare_fn_ty(&mut st, conv)
 }
 
-pub fn parse_trait_ref_data(data: &[u8], crate_num: int, pos: uint, tcx: ty::ctxt,
+pub fn parse_trait_ref_data(data: &[u8], crate_num: ast::CrateNum, pos: uint, tcx: ty::ctxt,
                             conv: conv_did) -> ty::TraitRef {
     let mut st = parse_state_from_data(data, crate_num, pos, tcx);
     parse_trait_ref(&mut st, conv)
@@ -251,7 +251,7 @@ fn parse_region(st: &mut PState, conv: conv_did) -> ty::Region {
     match next(st) {
       'b' => {
         assert_eq!(next(st), '[');
-        let id = parse_uint(st) as int;
+        let id = parse_uint(st) as ast::NodeId;
         assert_eq!(next(st), '|');
         let br = parse_bound_region(st, |x,y| conv(x,y));
         assert_eq!(next(st), ']');
@@ -259,7 +259,7 @@ fn parse_region(st: &mut PState, conv: conv_did) -> ty::Region {
       }
       'B' => {
         assert_eq!(next(st), '[');
-        let node_id = parse_uint(st) as int;
+        let node_id = parse_uint(st) as ast::NodeId;
         assert_eq!(next(st), '|');
         let index = parse_uint(st);
         assert_eq!(next(st), '|');
@@ -268,7 +268,7 @@ fn parse_region(st: &mut PState, conv: conv_did) -> ty::Region {
       }
       'f' => {
         assert_eq!(next(st), '[');
-        let id = parse_uint(st) as int;
+        let id = parse_uint(st) as ast::NodeId;
         assert_eq!(next(st), '|');
         let br = parse_bound_region(st, |x,y| conv(x,y));
         assert_eq!(next(st), ']');
@@ -276,7 +276,7 @@ fn parse_region(st: &mut PState, conv: conv_did) -> ty::Region {
                                     bound_region: br})
       }
       's' => {
-        let id = parse_uint(st) as int;
+        let id = parse_uint(st) as ast::NodeId;
         assert_eq!(next(st), '|');
         ty::ReScope(id)
       }
@@ -539,7 +539,7 @@ fn parse_bare_fn_ty(st: &mut PState, conv: conv_did) -> ty::BareFnTy {
 
 fn parse_sig(st: &mut PState, conv: conv_did) -> ty::FnSig {
     assert_eq!(next(st), '[');
-    let id = parse_uint(st) as int;
+    let id = parse_uint(st) as ast::NodeId;
     assert_eq!(next(st), '|');
     let mut inputs = ~[];
     while peek(st) != ']' {
@@ -572,12 +572,12 @@ pub fn parse_def_id(buf: &[u8]) -> ast::DefId {
     let def_part = buf.slice(colon_idx + 1u, len);
 
     let crate_num = match uint::parse_bytes(crate_part, 10u) {
-       Some(cn) => cn as int,
+       Some(cn) => cn as ast::CrateNum,
        None => fail!("internal error: parse_def_id: crate number expected, but found {:?}",
                      crate_part)
     };
     let def_num = match uint::parse_bytes(def_part, 10u) {
-       Some(dn) => dn as int,
+       Some(dn) => dn as ast::NodeId,
        None => fail!("internal error: parse_def_id: id expected, but found {:?}",
                      def_part)
     };
@@ -585,7 +585,7 @@ pub fn parse_def_id(buf: &[u8]) -> ast::DefId {
 }
 
 pub fn parse_type_param_def_data(data: &[u8], start: uint,
-                                 crate_num: int, tcx: ty::ctxt,
+                                 crate_num: ast::CrateNum, tcx: ty::ctxt,
                                  conv: conv_did) -> ty::TypeParameterDef
 {
     let mut st = parse_state_from_data(data, crate_num, start, tcx);
diff --git a/src/librustc/middle/astencode.rs b/src/librustc/middle/astencode.rs
index 7f8816bd6137d..5eb1bbab423e6 100644
--- a/src/librustc/middle/astencode.rs
+++ b/src/librustc/middle/astencode.rs
@@ -161,8 +161,7 @@ fn reserve_id_range(sess: Session,
     // Handle the case of an empty range:
     if from_id_range.empty() { return from_id_range; }
     let cnt = from_id_range.max - from_id_range.min;
-    assert!(cnt >= 0);
-    let to_id_min = sess.reserve_node_ids(cnt as uint);
+    let to_id_min = sess.reserve_node_ids(cnt);
     let to_id_max = to_id_min + cnt;
     ast_util::id_range { min: to_id_min, max: to_id_max }
 }
@@ -1210,7 +1209,7 @@ fn decode_side_tables(xcx: @ExtendedDecodeContext,
     let tbl_doc = ast_doc.get(c::tag_table as uint);
     do reader::docs(tbl_doc) |tag, entry_doc| {
         let id0 = entry_doc.get(c::tag_table_id as uint).as_int();
-        let id = xcx.tr_id(id0);
+        let id = xcx.tr_id(id0 as ast::NodeId);
 
         debug!(">> Side table document with tag 0x{:x} \
                 found for id {} (orig {})",
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index fefed79577958..359af9a0bf29c 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -169,7 +169,7 @@ pub struct field_ty {
 // the types of AST nodes.
 #[deriving(Eq,IterBytes)]
 pub struct creader_cache_key {
-    cnum: int,
+    cnum: CrateNum,
     pos: uint,
     len: uint
 }
diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index dacd7a09f9bb8..b888c8772d0d3 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -69,7 +69,7 @@ impl Eq for Ident {
 
 // this uint is a reference to a table stored in thread-local
 // storage.
-pub type SyntaxContext = uint;
+pub type SyntaxContext = u32;
 
 // the SCTable contains a table of SyntaxContext_'s. It
 // represents a flattened tree structure, to avoid having
@@ -87,8 +87,8 @@ pub struct SCTable {
 }
 
 // NB: these must be placed in any SCTable...
-pub static EMPTY_CTXT : uint = 0;
-pub static ILLEGAL_CTXT : uint = 1;
+pub static EMPTY_CTXT : SyntaxContext = 0;
+pub static ILLEGAL_CTXT : SyntaxContext = 1;
 
 #[deriving(Eq, Encodable, Decodable,IterBytes)]
 pub enum SyntaxContext_ {
@@ -109,10 +109,10 @@ pub enum SyntaxContext_ {
 
 /// A name is a part of an identifier, representing a string or gensym. It's
 /// the result of interning.
-pub type Name = uint;
+pub type Name = u32;
 
 /// A mark represents a unique id associated with a macro expansion
-pub type Mrk = uint;
+pub type Mrk = u32;
 
 impl<S:Encoder> Encodable<S> for Ident {
     fn encode(&self, s: &mut S) {
@@ -163,9 +163,9 @@ pub struct PathSegment {
     types: OptVec<Ty>,
 }
 
-pub type CrateNum = int;
+pub type CrateNum = u32;
 
-pub type NodeId = int;
+pub type NodeId = u32;
 
 #[deriving(Clone, TotalEq, TotalOrd, Eq, Encodable, Decodable, IterBytes, ToStr)]
 pub struct DefId {
diff --git a/src/libsyntax/ast_util.rs b/src/libsyntax/ast_util.rs
index 16846823e0c6f..cc74754cecbc5 100644
--- a/src/libsyntax/ast_util.rs
+++ b/src/libsyntax/ast_util.rs
@@ -18,7 +18,7 @@ use visit::Visitor;
 use visit;
 
 use std::hashmap::HashMap;
-use std::int;
+use std::u32;
 use std::local_data;
 use std::num;
 use std::option;
@@ -382,8 +382,8 @@ pub struct id_range {
 impl id_range {
     pub fn max() -> id_range {
         id_range {
-            min: int::max_value,
-            max: int::min_value,
+            min: u32::max_value,
+            max: u32::min_value,
         }
     }
 
@@ -803,9 +803,9 @@ pub fn display_sctable(table : &SCTable) {
 
 
 /// Add a value to the end of a vec, return its index
-fn idx_push<T>(vec: &mut ~[T], val: T) -> uint {
+fn idx_push<T>(vec: &mut ~[T], val: T) -> u32 {
     vec.push(val);
-    vec.len() - 1
+    (vec.len() - 1) as u32
 }
 
 /// Resolve a syntax object to a name, per MTWT.
@@ -917,7 +917,7 @@ pub fn mtwt_outer_mark(ctxt: SyntaxContext) -> Mrk {
 
 /// Push a name... unless it matches the one on top, in which
 /// case pop and discard (so two of the same marks cancel)
-pub fn xorPush(marks: &mut ~[uint], mark: uint) {
+pub fn xorPush(marks: &mut ~[Mrk], mark: Mrk) {
     if ((marks.len() > 0) && (getLast(marks) == mark)) {
         marks.pop();
     } else {
@@ -927,7 +927,7 @@ pub fn xorPush(marks: &mut ~[uint], mark: uint) {
 
 // get the last element of a mutable array.
 // FIXME #4903: , must be a separate procedure for now.
-pub fn getLast(arr: &~[Mrk]) -> uint {
+pub fn getLast(arr: &~[Mrk]) -> Mrk {
     *arr.last()
 }
 
@@ -1000,14 +1000,8 @@ mod test {
         assert_eq!(s.clone(),~[14]);
     }
 
-    // convert a list of uints to an @[ident]
-    // (ignores the interner completely)
-    fn uints_to_idents (uints: &~[uint]) -> @~[Ident] {
-        @uints.map(|u| Ident {name:*u, ctxt: EMPTY_CTXT})
-    }
-
-    fn id (u : uint, s: SyntaxContext) -> Ident {
-        Ident{name:u, ctxt: s}
+    fn id(n: Name, s: SyntaxContext) -> Ident {
+        Ident {name: n, ctxt: s}
     }
 
     // because of the SCTable, I now need a tidy way of
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 63f4f97889c6d..768c65ee6f9f3 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -502,12 +502,12 @@ fn mk_fresh_ident_interner() -> @ident_interner {
     @interner::StrInterner::prefill(init_vec)
 }
 
-static SELF_KEYWORD_NAME: uint = 8;
-static STATIC_KEYWORD_NAME: uint = 27;
-static STRICT_KEYWORD_START: uint = 32;
-static STRICT_KEYWORD_FINAL: uint = 65;
-static RESERVED_KEYWORD_START: uint = 66;
-static RESERVED_KEYWORD_FINAL: uint = 72;
+static SELF_KEYWORD_NAME: Name = 8;
+static STATIC_KEYWORD_NAME: Name = 27;
+static STRICT_KEYWORD_START: Name = 32;
+static STRICT_KEYWORD_FINAL: Name = 65;
+static RESERVED_KEYWORD_START: Name = 66;
+static RESERVED_KEYWORD_FINAL: Name = 72;
 
 // if an interner exists in TLS, return it. Otherwise, prepare a
 // fresh one.
diff --git a/src/libsyntax/util/interner.rs b/src/libsyntax/util/interner.rs
index 82249453ac24d..c144b36a86f5b 100644
--- a/src/libsyntax/util/interner.rs
+++ b/src/libsyntax/util/interner.rs
@@ -12,15 +12,17 @@
 // allows bidirectional lookup; i.e. given a value, one can easily find the
 // type, and vice versa.
 
+use ast::Name;
+
 use std::cmp::Equiv;
 use std::hashmap::HashMap;
 
 pub struct Interner<T> {
-    priv map: @mut HashMap<T, uint>,
+    priv map: @mut HashMap<T, Name>,
     priv vect: @mut ~[T],
 }
 
-// when traits can extend traits, we should extend index<uint,T> to get []
+// when traits can extend traits, we should extend index<Name,T> to get []
 impl<T:Eq + IterBytes + Hash + Freeze + Clone + 'static> Interner<T> {
     pub fn new() -> Interner<T> {
         Interner {
@@ -37,37 +39,37 @@ impl<T:Eq + IterBytes + Hash + Freeze + Clone + 'static> Interner<T> {
         rv
     }
 
-    pub fn intern(&self, val: T) -> uint {
+    pub fn intern(&self, val: T) -> Name {
         match self.map.find(&val) {
             Some(&idx) => return idx,
             None => (),
         }
 
         let vect = &mut *self.vect;
-        let new_idx = vect.len();
+        let new_idx = vect.len() as Name;
         self.map.insert(val.clone(), new_idx);
         vect.push(val);
         new_idx
     }
 
-    pub fn gensym(&self, val: T) -> uint {
+    pub fn gensym(&self, val: T) -> Name {
         let new_idx = {
             let vect = &*self.vect;
-            vect.len()
+            vect.len() as Name
         };
         // leave out of .map to avoid colliding
         self.vect.push(val);
         new_idx
     }
 
-    pub fn get(&self, idx: uint) -> T {
+    pub fn get(&self, idx: Name) -> T {
         self.vect[idx].clone()
     }
 
     pub fn len(&self) -> uint { let vect = &*self.vect; vect.len() }
 
     pub fn find_equiv<Q:Hash + IterBytes + Equiv<T>>(&self, val: &Q)
-                                              -> Option<uint> {
+                                              -> Option<Name> {
         match self.map.find_equiv(val) {
             Some(v) => Some(*v),
             None => None,
@@ -78,11 +80,11 @@ impl<T:Eq + IterBytes + Hash + Freeze + Clone + 'static> Interner<T> {
 // A StrInterner differs from Interner<String> in that it accepts
 // borrowed pointers rather than @ ones, resulting in less allocation.
 pub struct StrInterner {
-    priv map: @mut HashMap<@str, uint>,
+    priv map: @mut HashMap<@str, Name>,
     priv vect: @mut ~[@str],
 }
 
-// when traits can extend traits, we should extend index<uint,T> to get []
+// when traits can extend traits, we should extend index<Name,T> to get []
 impl StrInterner {
     pub fn new() -> StrInterner {
         StrInterner {
@@ -97,21 +99,21 @@ impl StrInterner {
         rv
     }
 
-    pub fn intern(&self, val: &str) -> uint {
+    pub fn intern(&self, val: &str) -> Name {
         match self.map.find_equiv(&val) {
             Some(&idx) => return idx,
             None => (),
         }
 
-        let new_idx = self.len();
+        let new_idx = self.len() as Name;
         let val = val.to_managed();
         self.map.insert(val, new_idx);
         self.vect.push(val);
         new_idx
     }
 
-    pub fn gensym(&self, val: &str) -> uint {
-        let new_idx = self.len();
+    pub fn gensym(&self, val: &str) -> Name {
+        let new_idx = self.len() as Name;
         // leave out of .map to avoid colliding
         self.vect.push(val.to_managed());
         new_idx
@@ -127,19 +129,19 @@ impl StrInterner {
 
     // create a gensym with the same name as an existing
     // entry.
-    pub fn gensym_copy(&self, idx : uint) -> uint {
-        let new_idx = self.len();
+    pub fn gensym_copy(&self, idx : Name) -> Name {
+        let new_idx = self.len() as Name;
         // leave out of map to avoid colliding
         self.vect.push(self.vect[idx]);
         new_idx
     }
 
-    pub fn get(&self, idx: uint) -> @str { self.vect[idx] }
+    pub fn get(&self, idx: Name) -> @str { self.vect[idx] }
 
     pub fn len(&self) -> uint { let vect = &*self.vect; vect.len() }
 
     pub fn find_equiv<Q:Hash + IterBytes + Equiv<@str>>(&self, val: &Q)
-                                                         -> Option<uint> {
+                                                         -> Option<Name> {
         match self.map.find_equiv(val) {
             Some(v) => Some(*v),
             None => None,