diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 7da857b48f6..3c2af3c85d3 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -7,7 +7,6 @@ import util.common.spanned;
 import util.common.ty_mach;
 
 type ident = str;
-type ty_param = ident;
 
 type name_ = rec(ident ident, vec[@ty] types);
 type name = spanned[name_];
@@ -17,6 +16,8 @@ type crate_num = int;
 type def_num = int;
 type def_id = tup(crate_num, def_num);
 
+type ty_param = rec(ident ident, def_id id);
+
 // Annotations added during successive passes.
 tag ann {
     ann_none;
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index f4874733aad..261ea1ad7dc 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -1039,10 +1039,15 @@ impure fn parse_block(parser p) -> ast.block {
     ret spanned(stmts.span, stmts.span, b);
 }
 
+impure fn parse_ty_param(parser p) -> ast.ty_param {
+    auto ident = parse_ident(p);
+    ret rec(ident=ident, id=p.next_def_id());
+}
+
 impure fn parse_ty_params(parser p) -> vec[ast.ty_param] {
     let vec[ast.ty_param] ty_params = vec();
     if (p.peek() == token.LBRACKET) {
-        auto f = parse_ident;   // FIXME: pass as lval directly
+        auto f = parse_ty_param;   // FIXME: pass as lval directly
         ty_params = parse_seq[ast.ty_param](token.LBRACKET, token.RBRACKET,
                                             some(token.COMMA), f, p).node;
     }