diff --git a/src/comp/metadata/creader.rs b/src/comp/metadata/creader.rs
index f5757f56bee..d9d48914c07 100644
--- a/src/comp/metadata/creader.rs
+++ b/src/comp/metadata/creader.rs
@@ -48,7 +48,7 @@ type env =
     @rec(session::session sess,
          @hashmap[str, int] crate_cache,
          vec[str] library_search_paths,
-         mutable int next_crate_num);
+         mutable ast::crate_num next_crate_num);
 
 fn visit_view_item(env e, &@ast::view_item i) {
     alt (i.node) {
@@ -210,7 +210,7 @@ fn get_metadata_section(str filename) -> option::t[vec[u8]] {
     ret option::none[vec[u8]];
 }
 
-fn load_library_crate(&session::session sess, span span, int cnum,
+fn load_library_crate(&session::session sess, span span, ast::crate_num cnum,
                       &ast::ident ident, &(@ast::meta_item)[] metas,
                       &vec[str] library_search_paths) {
     alt (find_library_crate(sess, ident, metas, library_search_paths)) {
diff --git a/src/comp/metadata/cstore.rs b/src/comp/metadata/cstore.rs
index 80690a46263..1ddb378dab3 100644
--- a/src/comp/metadata/cstore.rs
+++ b/src/comp/metadata/cstore.rs
@@ -11,7 +11,7 @@ type crate_metadata = rec(str name, vec[u8] data);
 // Map from node_id's of local use statements to crate numbers
 type use_crate_map = map::hashmap[ast::node_id, ast::crate_num];
 
-type cstore = @rec(map::hashmap[int, crate_metadata] metas,
+type cstore = @rec(map::hashmap[ast::crate_num, crate_metadata] metas,
                    use_crate_map use_crate_map,
                    mutable vec[str] used_crate_files,
                    mutable vec[str] used_libraries,
@@ -27,15 +27,15 @@ fn mk_cstore() -> cstore {
              mutable used_link_args = []);
 }
 
-fn get_crate_data(&cstore cstore, int cnum) -> crate_metadata {
+fn get_crate_data(&cstore cstore, ast::crate_num cnum) -> crate_metadata {
     ret cstore.metas.get(cnum);
 }
 
-fn set_crate_data(&cstore cstore, int cnum, &crate_metadata data) {
+fn set_crate_data(&cstore cstore, ast::crate_num cnum, &crate_metadata data) {
     cstore.metas.insert(cnum, data);
 }
 
-fn have_crate_data(&cstore cstore, int cnum) -> bool {
+fn have_crate_data(&cstore cstore, ast::crate_num cnum) -> bool {
     ret cstore.metas.contains_key(cnum);
 }
 
@@ -72,7 +72,8 @@ fn get_used_link_args(&cstore cstore) -> vec[str] {
     ret cstore.used_link_args;
 }
 
-fn add_use_stmt_cnum(&cstore cstore, ast::node_id use_id, int cnum) {
+fn add_use_stmt_cnum(&cstore cstore, ast::node_id use_id,
+                     ast::crate_num cnum) {
     cstore.use_crate_map.insert(use_id, cnum);
 }
 
diff --git a/src/comp/metadata/decoder.rs b/src/comp/metadata/decoder.rs
index 3e9d3a82cc7..91e97c8d835 100644
--- a/src/comp/metadata/decoder.rs
+++ b/src/comp/metadata/decoder.rs
@@ -82,8 +82,9 @@ fn variant_tag_id(&ebml::doc d) -> ast::def_id {
     ret parse_def_id(ebml::doc_data(tagdoc));
 }
 
-fn item_type(&ebml::doc item, int this_cnum, ty::ctxt tcx) -> ty::t {
-    fn parse_external_def_id(int this_cnum, str s) -> ast::def_id {
+fn item_type(&ebml::doc item, ast::crate_num this_cnum,
+             ty::ctxt tcx) -> ty::t {
+    fn parse_external_def_id(ast::crate_num this_cnum, str s) -> ast::def_id {
         // FIXME: This is completely wrong when linking against a crate
         // that, in turn, links against another crate. We need a mapping
         // from crate ID to crate "meta" attributes as part of the crate
@@ -107,7 +108,8 @@ fn item_ty_param_count(&ebml::doc item) -> uint {
     ret ty_param_count;
 }
 
-fn tag_variant_ids(&ebml::doc item, int this_cnum) -> vec[ast::def_id] {
+fn tag_variant_ids(&ebml::doc item,
+                   ast::crate_num this_cnum) -> vec[ast::def_id] {
     let vec[ast::def_id] ids = [];
     auto v = tag_items_data_item_variant;
     for each (ebml::doc p in ebml::tagged_docs(item, v)) {
@@ -136,15 +138,16 @@ fn resolve_path(vec[ast::ident] path, vec[u8] data) -> vec[ast::def_id] {
 }
 
 // Crate metadata queries
-fn lookup_defs(session::session sess, int cnum, vec[ast::ident] path) ->
-   vec[ast::def] {
+fn lookup_defs(session::session sess, ast::crate_num cnum,
+               vec[ast::ident] path) -> vec[ast::def] {
     auto data = cstore::get_crate_data(sess.get_cstore(), cnum).data;
     ret vec::map(bind lookup_def(cnum, data, _), resolve_path(path, data));
 }
 
 
 // FIXME doesn't yet handle re-exported externals
-fn lookup_def(int cnum, vec[u8] data, &ast::def_id did_) -> ast::def {
+fn lookup_def(ast::crate_num cnum, vec[u8] data,
+              &ast::def_id did_) -> ast::def {
     auto item = lookup_item(did_._1, data);
     auto kind_ch = item_kind(item);
     auto did = tup(cnum, did_._1);