diff --git a/src/comp/metadata/encoder.rs b/src/comp/metadata/encoder.rs
index 537e40761af..b842b900e6c 100644
--- a/src/comp/metadata/encoder.rs
+++ b/src/comp/metadata/encoder.rs
@@ -213,14 +213,14 @@ fn encode_type(ecx: &@encode_ctxt, ebml_w: &ebml::writer, typ: ty::t) {
 
 fn encode_symbol(ecx: &@encode_ctxt, ebml_w: &ebml::writer, id: node_id) {
     ebml::start_tag(ebml_w, tag_items_data_item_symbol);
-    ebml_w.writer.write(str::bytes(ecx.ccx.item_symbols.get(id)));
+    ebml_w.writer.write(istr::bytes(ecx.ccx.item_symbols.get(id)));
     ebml::end_tag(ebml_w);
 }
 
 fn encode_discriminant(ecx: &@encode_ctxt, ebml_w: &ebml::writer,
                        id: node_id) {
     ebml::start_tag(ebml_w, tag_items_data_item_symbol);
-    ebml_w.writer.write(str::bytes(ecx.ccx.discrim_symbols.get(id)));
+    ebml_w.writer.write(istr::bytes(ecx.ccx.discrim_symbols.get(id)));
     ebml::end_tag(ebml_w);
 }
 
diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index a5fb80433bd..8ae36ce6868 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -5858,7 +5858,7 @@ fn register_fn_pair(cx: &@crate_ctxt, ps: str, llfnty: TypeRef,
     let gvar =
         create_fn_pair(cx, ps, llfnty, llfn, cx.sess.get_opts().library);
     cx.item_ids.insert(id, llfn);
-    cx.item_symbols.insert(id, ps);
+    cx.item_symbols.insert(id, istr::from_estr(ps));
     cx.fn_pairs.insert(id, gvar);
 }
 
@@ -6101,7 +6101,7 @@ fn collect_item_1(ccx: @crate_ctxt, i: &@ast::item, pt: &[str],
         let g = istr::as_buf(s, { |buf|
             llvm::LLVMAddGlobal(ccx.llmod, type_of(ccx, i.span, typ), buf)
         });
-        ccx.item_symbols.insert(i.id, istr::to_estr(s));
+        ccx.item_symbols.insert(i.id, s);
         ccx.consts.insert(i.id, g);
       }
       _ { }
@@ -6198,7 +6198,7 @@ fn trans_constant(ccx: @crate_ctxt, it: &@ast::item, pt: &[str],
                 llvm::LLVMSetGlobalConstant(discrim_gvar, True);
             }
             ccx.discrims.insert(variant.node.id, discrim_gvar);
-            ccx.discrim_symbols.insert(variant.node.id, istr::to_estr(s));
+            ccx.discrim_symbols.insert(variant.node.id, s);
             i += 1u;
         }
       }
@@ -6428,7 +6428,7 @@ fn trans_crate(sess: &session::session, crate: &@ast::crate, tcx: &ty::ctxt,
     let tydescs = map::mk_hashmap::<ty::t, @tydesc_info>(hasher, eqer);
     let lltypes = map::mk_hashmap::<ty::t, TypeRef>(hasher, eqer);
     let sha1s = map::mk_hashmap::<ty::t, istr>(hasher, eqer);
-    let short_names = map::mk_hashmap::<ty::t, str>(hasher, eqer);
+    let short_names = map::mk_hashmap::<ty::t, istr>(hasher, eqer);
     let sha = std::sha1::mk_sha1();
     let ccx =
         @{sess: sess,
@@ -6439,13 +6439,13 @@ fn trans_crate(sess: &session::session, crate: &@ast::crate, tcx: &ty::ctxt,
           intrinsics: intrinsics,
           item_ids: new_int_hash::<ValueRef>(),
           ast_map: amap,
-          item_symbols: new_int_hash::<str>(),
+          item_symbols: new_int_hash::<istr>(),
           mutable main_fn: none::<ValueRef>,
           link_meta: link::build_link_meta(sess, *crate,
                                            istr::from_estr(output), sha),
           tag_sizes: tag_sizes,
           discrims: new_int_hash::<ValueRef>(),
-          discrim_symbols: new_int_hash::<str>(),
+          discrim_symbols: new_int_hash::<istr>(),
           fn_pairs: new_int_hash::<ValueRef>(),
           consts: new_int_hash::<ValueRef>(),
           obj_methods: new_int_hash::<()>(),
diff --git a/src/comp/middle/trans_common.rs b/src/comp/middle/trans_common.rs
index e4c842bdf4f..698db358cac 100644
--- a/src/comp/middle/trans_common.rs
+++ b/src/comp/middle/trans_common.rs
@@ -131,12 +131,12 @@ type crate_ctxt =
      intrinsics: hashmap<istr, ValueRef>,
      item_ids: hashmap<ast::node_id, ValueRef>,
      ast_map: ast_map::map,
-     item_symbols: hashmap<ast::node_id, str>,
+     item_symbols: hashmap<ast::node_id, istr>,
      mutable main_fn: option::t<ValueRef>,
      link_meta: link::link_meta,
      tag_sizes: hashmap<ty::t, uint>,
      discrims: hashmap<ast::node_id, ValueRef>,
-     discrim_symbols: hashmap<ast::node_id, str>,
+     discrim_symbols: hashmap<ast::node_id, istr>,
      fn_pairs: hashmap<ast::node_id, ValueRef>,
      consts: hashmap<ast::node_id, ValueRef>,
      obj_methods: hashmap<ast::node_id, ()>,
@@ -147,7 +147,7 @@ type crate_ctxt =
      names: namegen,
      sha: std::sha1::sha1,
      type_sha1s: hashmap<ty::t, istr>,
-     type_short_names: hashmap<ty::t, str>,
+     type_short_names: hashmap<ty::t, istr>,
      tcx: ty::ctxt,
      mut_map: alias::mut_map,
      stats: stats,
diff --git a/src/comp/middle/trans_objects.rs b/src/comp/middle/trans_objects.rs
index 862bb8a20ff..2add4d17d8e 100644
--- a/src/comp/middle/trans_objects.rs
+++ b/src/comp/middle/trans_objects.rs
@@ -936,7 +936,7 @@ fn process_normal_mthd(cx: @local_ctxt, m: @ast::method, self_ty: ty::t,
     // item_ids map, together with the ValueRef that points to where that
     // method's definition will be in the executable.
     cx.ccx.item_ids.insert(m.node.id, llfn);
-    cx.ccx.item_symbols.insert(m.node.id, istr::to_estr(s));
+    cx.ccx.item_symbols.insert(m.node.id, s);
     trans_fn(mcx, m.span, m.node.meth, llfn, some(self_ty), ty_params,
              m.node.id);