diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index 539dc3e1f00098f3bc505913894a3456fbae1f51..9b9f80c741b263a55c3580473472660ca09e815a 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -1730,8 +1730,15 @@ pub fn copy_args_to_allocas(fcx: fn_ctxt,
         // We really should do this regardless of whether self is owned, but
         // it doesn't work right with default method impls yet. (FIXME: #2794)
         if slf.is_owned {
-            let self_val = PointerCast(bcx, slf.v,
-                                       T_ptr(type_of(bcx.ccx(), slf.t)));
+            let self_val = if datum::appropriate_mode(slf.t).is_by_value() {
+                let tmp = BitCast(bcx, slf.v, type_of(bcx.ccx(), slf.t));
+                let alloc = alloc_ty(bcx, slf.t);
+                Store(bcx, tmp, alloc);
+                alloc
+            } else {
+                PointerCast(bcx, slf.v, T_ptr(type_of(bcx.ccx(), slf.t)))
+            };
+
             fcx.llself = Some(ValSelfData {v: self_val, ..slf});
             add_clean(bcx, self_val, slf.t);
         }