diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 7106515083e..11db3eedc31 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -33,6 +33,7 @@ tag def {
     def_variant(def_id /* tag */, def_id /* variant */);
     def_ty(def_id);
     def_ty_arg(def_id);
+    def_binding(def_id);
 }
 
 type crate = spanned[crate_];
@@ -124,7 +125,7 @@ tag decl_ {
     decl_item(@item);
 }
 
-type arm = rec(@pat pat, block block);
+type arm = rec(@pat pat, block block, hashmap[ident,def_id] index);
 
 type elt = rec(mutability mut, @expr expr);
 type field = rec(mutability mut, ident ident, @expr expr);
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index f8db2f71b14..decb28e1f47 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -817,8 +817,9 @@ impure fn parse_alt_expr(parser p) -> @ast.expr {
                 expect(p, token.LPAREN);
                 auto pat = parse_pat(p);
                 expect(p, token.RPAREN);
+                auto index = index_arm(pat);
                 auto block = parse_block(p);
-                arms += vec(rec(pat=pat, block=block));
+                arms += vec(rec(pat=pat, block=block, index=index));
             }
             case (token.RBRACE) { /* empty */ }
             case (?tok) {
@@ -1082,6 +1083,24 @@ fn index_block(vec[@ast.stmt] stmts, option.t[@ast.expr] expr) -> ast.block_ {
     ret rec(stmts=stmts, expr=expr, index=index);
 }
 
+fn index_arm(@ast.pat pat) -> hashmap[ast.ident,ast.def_id] {
+    fn do_index_arm(&hashmap[ast.ident,ast.def_id] index, @ast.pat pat) {
+        alt (pat.node) {
+            case (ast.pat_bind(?i, ?def_id, _)) { index.insert(i, def_id); }
+            case (ast.pat_wild(_)) { /* empty */ }
+            case (ast.pat_tag(_, ?pats, _)) {
+                for (@ast.pat p in pats) {
+                    do_index_arm(index, p);
+                }
+            }
+        }
+    }
+
+    auto index = new_str_hash[ast.def_id]();
+    do_index_arm(index, pat);
+    ret index;
+}
+
 fn stmt_to_expr(@ast.stmt stmt) -> option.t[@ast.expr] {
     alt (stmt.node) {
         case (ast.stmt_expr(?e)) { ret some[@ast.expr](e); }
diff --git a/src/comp/middle/fold.rs b/src/comp/middle/fold.rs
index 54e098384c5..521b433e756 100644
--- a/src/comp/middle/fold.rs
+++ b/src/comp/middle/fold.rs
@@ -574,7 +574,7 @@ fn fold_arm[ENV](&ENV env, ast_fold[ENV] fld, &arm a) -> arm {
     let ENV env_ = fld.update_env_for_arm(env, a);
     auto ppat = fold_pat(env_, fld, a.pat);
     auto bblock = fold_block(env_, fld, a.block);
-    ret rec(pat=ppat, block=bblock);
+    ret rec(pat=ppat, block=bblock, index=a.index);
 }
 
 fn fold_arg[ENV](&ENV env, ast_fold[ENV] fld, &arg a) -> arg {
diff --git a/src/comp/middle/resolve.rs b/src/comp/middle/resolve.rs
index 491d9e4a4c2..08175e7893e 100644
--- a/src/comp/middle/resolve.rs
+++ b/src/comp/middle/resolve.rs
@@ -18,6 +18,7 @@ tag scope {
     scope_crate(@ast.crate);
     scope_item(@ast.item);
     scope_block(ast.block);
+    scope_arm(ast.arm);
 }
 
 type env = rec(list[scope] scopes,
@@ -120,6 +121,15 @@ fn lookup_name(&env e, ast.ident i) -> option.t[def] {
                     case (_) { /* fall through */  }
                 }
             }
+
+            case (scope_arm(?a)) {
+                alt (a.index.find(i)) {
+                    case (some[ast.def_id](?did)) {
+                        ret some[def](ast.def_binding(did));
+                    }
+                    case (_) { /* fall through */  }
+                }
+            }
         }
         ret none[def];
     }
@@ -189,6 +199,11 @@ fn update_env_for_block(&env e, &ast.block b) -> env {
     ret rec(scopes = cons[scope](scope_block(b), @e.scopes) with e);
 }
 
+fn update_env_for_arm(&env e, &ast.arm p) -> env {
+    log "update_env_for_arm";
+    ret rec(scopes = cons[scope](scope_arm(p), @e.scopes) with e);
+}
+
 fn resolve_crate(session.session sess, @ast.crate crate) -> @ast.crate {
 
     let fold.ast_fold[env] fld = fold.new_identity_fold[env]();
@@ -197,7 +212,8 @@ fn resolve_crate(session.session sess, @ast.crate crate) -> @ast.crate {
                 fold_ty_path = bind fold_ty_path(_,_,_,_),
                 update_env_for_crate = bind update_env_for_crate(_,_),
                 update_env_for_item = bind update_env_for_item(_,_),
-                update_env_for_block = bind update_env_for_block(_,_)
+                update_env_for_block = bind update_env_for_block(_,_),
+                update_env_for_arm = bind update_env_for_arm(_,_)
                 with *fld );
 
     auto e = rec(scopes = nil[scope],