diff --git a/basis/compiler/cfg/intrinsics/slots/slots.factor b/basis/compiler/cfg/intrinsics/slots/slots.factor
index a28c95f81f..8a86c984fe 100644
--- a/basis/compiler/cfg/intrinsics/slots/slots.factor
+++ b/basis/compiler/cfg/intrinsics/slots/slots.factor
@@ -1,9 +1,10 @@
 ! Copyright (C) 2008, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: layouts namespaces kernel accessors sequences classes.algebra
-fry compiler.tree.propagation.info compiler.cfg.stacks compiler.cfg.hats
-compiler.cfg.registers compiler.cfg.instructions
-compiler.cfg.utilities compiler.cfg.builder.blocks ;
+USING: layouts namespaces kernel accessors sequences
+classes.algebra locals compiler.tree.propagation.info
+compiler.cfg.stacks compiler.cfg.hats compiler.cfg.registers
+compiler.cfg.instructions compiler.cfg.utilities
+compiler.cfg.builder.blocks compiler.constants ;
 IN: compiler.cfg.intrinsics.slots
 
 : value-tag ( info -- n ) class>> class-tag ; inline
@@ -30,18 +31,31 @@ IN: compiler.cfg.intrinsics.slots
         ds-push
     ] [ drop emit-primitive ] if ;
 
-: (emit-set-slot) ( infos -- )
-    [ first class>> immediate class<= ]
-    [ [ 3inputs ] [ second value-tag ] bi* ^^tag-offset>slot ] bi
-    [ ##set-slot ]
-    [ '[ _ drop _ _ next-vreg next-vreg ##write-barrier ] unless ] 3bi ;
+: emit-write-barrier? ( infos -- ? )
+    first class>> immediate class<= not ;
 
-: (emit-set-slot-imm) ( infos -- )
+:: (emit-set-slot) ( infos -- )
+    3inputs :> slot :> obj :> src
+
+    slot infos second value-tag ^^tag-offset>slot :> slot
+
+    src obj slot ##set-slot
+
+    infos emit-write-barrier?
+    [ obj slot next-vreg next-vreg ##write-barrier ] when ;
+
+:: (emit-set-slot-imm) ( infos -- )
     ds-drop
-    [ first class>> immediate class<= ]
-    [ [ 2inputs ] [ [ third literal>> ] [ second value-tag ] bi ] bi* ] bi
-    '[ _ ##set-slot-imm ]
-    [ '[ _ drop _ _ cells next-vreg next-vreg ##write-barrier-imm ] unless ] 3bi ;
+
+    2inputs :> obj :> src
+
+    infos third literal>> :> slot
+    infos second value-tag :> tag
+
+    src obj slot tag ##set-slot-imm
+
+    infos emit-write-barrier?
+    [ obj slot tag slot-offset next-vreg next-vreg ##write-barrier-imm ] when ;
 
 : emit-set-slot ( node -- )
     dup node-input-infos
diff --git a/basis/compiler/constants/constants.factor b/basis/compiler/constants/constants.factor
index f6c6573be1..a22d522809 100644
--- a/basis/compiler/constants/constants.factor
+++ b/basis/compiler/constants/constants.factor
@@ -10,19 +10,21 @@ CONSTANT: deck-bits 18
 : card-mark ( -- n ) HEX: 40 HEX: 80 bitor ; inline
 
 ! These constants must match vm/layouts.h
-: header-offset ( -- n ) object tag-number neg ; inline
+: slot-offset ( slot tag -- n ) [ bootstrap-cells ] dip - ; inline
+
+: header-offset ( -- n ) 0 object tag-number slot-offset ; inline
 : float-offset ( -- n ) 8 float tag-number - ; inline
-: string-offset ( -- n ) 4 bootstrap-cells string tag-number - ; inline
-: string-aux-offset ( -- n ) 2 bootstrap-cells string tag-number - ; inline
-: profile-count-offset ( -- n ) 8 bootstrap-cells \ word tag-number - ; inline
-: byte-array-offset ( -- n ) 2 bootstrap-cells byte-array tag-number - ; inline
-: alien-offset ( -- n ) 3 bootstrap-cells alien tag-number - ; inline
-: underlying-alien-offset ( -- n ) bootstrap-cell alien tag-number - ; inline
-: tuple-class-offset ( -- n ) bootstrap-cell tuple tag-number - ; inline
-: word-xt-offset ( -- n ) 10 bootstrap-cells \ word tag-number - ; inline
-: quot-xt-offset ( -- n ) 4 bootstrap-cells quotation tag-number - ; inline
-: word-code-offset ( -- n ) 11 bootstrap-cells \ word tag-number - ; inline
-: array-start-offset ( -- n ) 2 bootstrap-cells array tag-number - ; inline
+: string-offset ( -- n ) 4 string tag-number slot-offset ; inline
+: string-aux-offset ( -- n ) 2 string tag-number slot-offset ; inline
+: profile-count-offset ( -- n ) 8 \ word tag-number slot-offset ; inline
+: byte-array-offset ( -- n ) 2 byte-array tag-number slot-offset ; inline
+: alien-offset ( -- n ) 3 alien tag-number slot-offset ; inline
+: underlying-alien-offset ( -- n ) 1 alien tag-number slot-offset ; inline
+: tuple-class-offset ( -- n ) 1 tuple tag-number slot-offset ; inline
+: word-xt-offset ( -- n ) 10 \ word tag-number slot-offset ; inline
+: quot-xt-offset ( -- n ) 4 quotation tag-number slot-offset ; inline
+: word-code-offset ( -- n ) 11 \ word tag-number slot-offset ; inline
+: array-start-offset ( -- n ) 2 array tag-number slot-offset ; inline
 : compiled-header-size ( -- n ) 4 bootstrap-cells ; inline
 
 ! Relocation classes
diff --git a/basis/cpu/x86/x86.factor b/basis/cpu/x86/x86.factor
index 4a3545a5ba..af2d75f02d 100644
--- a/basis/cpu/x86/x86.factor
+++ b/basis/cpu/x86/x86.factor
@@ -93,7 +93,7 @@ M: x86 %return ( -- ) 0 RET ;
     0 <repetition> % ;
 
 :: (%slot-imm) ( obj slot tag -- op )
-    obj slot cells tag - [+] ; inline
+    obj slot tag slot-offset [+] ; inline
 
 M: x86 %slot ( dst obj slot -- ) [+] MOV ;
 M: x86 %slot-imm ( dst obj slot tag -- ) (%slot-imm) MOV ;
@@ -395,8 +395,7 @@ M:: x86 %allot ( dst size class nursery-ptr -- )
 
 :: (%write-barrier) ( src slot temp1 temp2 -- )
     ! Compute slot address.
-    temp1 src MOV
-    temp1 slot ADD
+    temp1 src slot [+] LEA
 
     ! Mark the card
     temp1 card-bits SHR