diff --git a/src/comp/middle/mut.rs b/src/comp/middle/mut.rs
index 802fbbe7e40..2866d71e004 100644
--- a/src/comp/middle/mut.rs
+++ b/src/comp/middle/mut.rs
@@ -24,6 +24,7 @@ fn expr_root(tcx: ty::ctxt, ex: @expr, autoderef: bool) ->
               }
               ty::ty_uniq(mt) {
                 ds += [@{mut: mt.mut != imm, kind: unbox, outer_t: t}];
+                t = mt.ty;
               }
               ty::ty_res(_, inner, tps) {
                 ds += [@{mut: false, kind: unbox, outer_t: t}];
diff --git a/src/test/run-pass/unique-alt-discrim.rs b/src/test/run-pass/unique-alt-discrim.rs
new file mode 100644
index 00000000000..ad9b6ed2ce8
--- /dev/null
+++ b/src/test/run-pass/unique-alt-discrim.rs
@@ -0,0 +1,8 @@
+// Issue #961
+
+fn altsimple() {
+    alt ~true {
+      _ { }
+    }
+}
+fn main() { }
\ No newline at end of file