diff --git a/src/comp/back/upcall.rs b/src/comp/back/upcall.rs
index 11883da6a0d8..31ee139c524e 100644
--- a/src/comp/back/upcall.rs
+++ b/src/comp/back/upcall.rs
@@ -57,20 +57,17 @@ fn declare_upcalls(targ_cfg: @session::config,
                              T_ptr(T_i8()),
                              size_t]),
           malloc:
-              d("malloc", [T_ptr(tydesc_type)],
-                T_ptr(T_i8())),
+              d("malloc", [T_ptr(tydesc_type)], T_ptr(T_i8())),
           free:
               dv("free", [T_ptr(T_i8())]),
           validate_box:
               dv("validate_box", [T_ptr(T_i8())]),
           shared_malloc:
-              d("shared_malloc", [size_t, T_ptr(tydesc_type)],
-                T_ptr(T_i8())),
+              d("shared_malloc", [size_t], T_ptr(T_i8())),
           shared_free:
               dv("shared_free", [T_ptr(T_i8())]),
           shared_realloc:
-              d("shared_realloc", [T_ptr(T_i8()), size_t],
-                T_ptr(T_i8())),
+              d("shared_realloc", [T_ptr(T_i8()), size_t], T_ptr(T_i8())),
           mark:
               d("mark", [T_ptr(T_i8())], int_t),
           create_shared_type_desc:
diff --git a/src/comp/middle/trans/base.rs b/src/comp/middle/trans/base.rs
index c7661183a48f..02d6106ca566 100644
--- a/src/comp/middle/trans/base.rs
+++ b/src/comp/middle/trans/base.rs
@@ -481,12 +481,7 @@ fn GEP_enum(cx: block, llblobptr: ValueRef, enum_id: ast::def_id,
 // and a size indicating how much space we want malloc'd.
 fn trans_shared_malloc(cx: block, llptr_ty: TypeRef, llsize: ValueRef)
    -> result {
-    // FIXME: need a table to collect tydesc globals.
-
-    let tydesc = C_null(T_ptr(cx.ccx().tydesc_type));
-    let rval =
-        Call(cx, cx.ccx().upcalls.shared_malloc,
-             [llsize, tydesc]);
+    let rval = Call(cx, cx.ccx().upcalls.shared_malloc, [llsize]);
     ret rslt(cx, PointerCast(cx, rval, llptr_ty));
 }
 
diff --git a/src/comp/middle/trans/closure.rs b/src/comp/middle/trans/closure.rs
index cb2fff553fef..b7b5b910041c 100644
--- a/src/comp/middle/trans/closure.rs
+++ b/src/comp/middle/trans/closure.rs
@@ -627,7 +627,7 @@ fn make_opaque_cbox_take_glue(
 
         // Allocate memory, update original ptr, and copy existing data
         let malloc = ccx.upcalls.shared_malloc;
-        let cbox_out = Call(bcx, malloc, [sz, tydesc]);
+        let cbox_out = Call(bcx, malloc, [sz]);
         let cbox_out = PointerCast(bcx, cbox_out, llopaquecboxty);
         let {bcx, val: _} = call_memmove(bcx, cbox_out, cbox_in, sz);
         Store(bcx, cbox_out, cboxptr);
diff --git a/src/rt/rust_upcall.cpp b/src/rt/rust_upcall.cpp
index fcd9483eb632..affaa3e8f9c8 100644
--- a/src/rt/rust_upcall.cpp
+++ b/src/rt/rust_upcall.cpp
@@ -217,7 +217,6 @@ upcall_validate_box(rust_opaque_box* ptr) {
 struct s_shared_malloc_args {
     uintptr_t retval;
     size_t nbytes;
-    type_desc *td;
 };
 
 extern "C" CDECL void
@@ -225,21 +224,17 @@ upcall_s_shared_malloc(s_shared_malloc_args *args) {
     rust_task *task = rust_task_thread::get_task();
     LOG_UPCALL_ENTRY(task);
 
-    LOG(task, mem,
-        "upcall shared_malloc(%" PRIdPTR ", 0x%" PRIxPTR ")",
-        args->nbytes, args->td);
+    LOG(task, mem, "upcall shared_malloc(%" PRIdPTR ")", args->nbytes);
     void *p = task->kernel->malloc(args->nbytes, "shared malloc");
     memset(p, '\0', args->nbytes);
-    LOG(task, mem,
-        "upcall shared_malloc(%" PRIdPTR ", 0x%" PRIxPTR
-        ") = 0x%" PRIxPTR,
-        args->nbytes, args->td, (uintptr_t)p);
+    LOG(task, mem, "upcall shared_malloc(%" PRIdPTR ") = 0x%" PRIxPTR,
+        args->nbytes, (uintptr_t)p);
     args->retval = (uintptr_t) p;
 }
 
 extern "C" CDECL uintptr_t
-upcall_shared_malloc(size_t nbytes, type_desc *td) {
-    s_shared_malloc_args args = {0, nbytes, td};
+upcall_shared_malloc(size_t nbytes) {
+    s_shared_malloc_args args = {0, nbytes};
     UPCALL_SWITCH_STACK(&args, upcall_s_shared_malloc);
     return args.retval;
 }