diff --git a/src/comp/back/x86.rs b/src/comp/back/x86.rs
index 0ed79db453c..345603bb710 100644
--- a/src/comp/back/x86.rs
+++ b/src/comp/back/x86.rs
@@ -212,10 +212,10 @@ fn upcall_glue(int n_args) -> vec[str] {
         + store_esp_to_rust_sp_second_arg()
         + load_esp_from_runtime_sp_second_arg()
 
-        + vec("subl  $" + wstr(n_args + 1) + ", %esp   # esp -= args",
+        + vec("subl  $" + wstr(n_args) + ", %esp   # esp -= args",
               "andl  $~0xf, %esp    # align esp down")
 
-        + _vec.init_fn[str](carg, (n_args + 1) as uint)
+        + _vec.init_fn[str](carg, (n_args) as uint)
 
         +  vec("movl  %edx, %edi     # save task from edx to edi",
                "call  *%ecx          # call *%ecx",
@@ -268,7 +268,7 @@ fn get_module_asm() -> str {
                       rust_yield_glue()))
 
         + _vec.init_fn[str](bind decl_upcall_glue(align, prefix, _),
-                            abi.n_upcall_glues as uint);
+                            (abi.n_upcall_glues + 1) as uint);
 
     ret _str.connect(glues, "\n\n");
 }
diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index 7bea575f9be..f119681b0c2 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -832,8 +832,7 @@ fn decl_upcall_glue(ModuleRef llmod, type_names tn, uint _n) -> ValueRef {
     let int n = _n as int;
     let str s = abi.upcall_glue_name(n);
     let vec[TypeRef] args =
-        vec(T_int(),     // callee
-            T_int()) // taskptr
+        vec(T_int())     // callee
         + _vec.init_elt[TypeRef](T_int(), n as uint);
 
     ret decl_fastcall_fn(llmod, s, T_fn(args, T_int()));
@@ -864,7 +863,7 @@ fn trans_upcall2(builder b, @glue_fns glues, ValueRef lltaskptr,
                  &hashmap[str, ValueRef] upcalls,
                  type_names tn, ModuleRef llmod, str name,
                  vec[ValueRef] args) -> ValueRef {
-    let int n = _vec.len[ValueRef](args) as int;
+    let int n = (_vec.len[ValueRef](args) as int) + 1;
     let ValueRef llupcall = get_upcall(upcalls, tn, llmod, name, n);
     llupcall = llvm.LLVMConstPointerCast(llupcall, T_int());
 
@@ -6098,7 +6097,7 @@ fn make_glues(ModuleRef llmod, type_names tn) -> @glue_fns {
 
              upcall_glues =
              _vec.init_fn[ValueRef](bind decl_upcall_glue(llmod, tn, _),
-                                    abi.n_upcall_glues as uint),
+                                    abi.n_upcall_glues + 1 as uint),
              no_op_type_glue = decl_no_op_type_glue(llmod, tn),
              memcpy_glue = decl_memcpy_glue(llmod),
              bzero_glue = decl_bzero_glue(llmod),