diff --git a/hoax/compile-ops.rkt b/hoax/compile-ops.rkt
index 90bba9b..7163b5f 100644
--- a/hoax/compile-ops.rkt
+++ b/hoax/compile-ops.rkt
@@ -65,16 +65,13 @@
           (Add rbx 8))]
     ['unbox
      (seq (assert-box rax)
-          (Xor rax type-box)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-box))))]
     ['car
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 8)))]
+          (Mov rax (Offset rax (- 8 type-cons))))]
     ['cdr
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-cons))))]
 
     ['empty? (seq (Cmp rax (value->bits '())) if-equal)]
     ['cons? (type-pred ptr-mask type-cons)]
@@ -85,10 +82,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-vector rax)
-            (Xor rax type-vect)
-            (Cmp rax 0)
+            (Cmp rax type-vect)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-vect)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
@@ -98,10 +94,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-string rax)
-            (Xor rax type-str)
-            (Cmp rax 0)
+            (Cmp rax type-str)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-str)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
diff --git a/hustle/compile-ops.rkt b/hustle/compile-ops.rkt
index da59401..c804998 100644
--- a/hustle/compile-ops.rkt
+++ b/hustle/compile-ops.rkt
@@ -63,16 +63,13 @@
           (Add rbx 8))]
     ['unbox
      (seq (assert-box rax)
-          (Xor rax type-box)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-box))))]
     ['car
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 8)))]
+          (Mov rax (Offset rax (- 8 type-cons))))]
     ['cdr
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-cons))))]
 
     ['empty? (seq (Cmp rax (value->bits '())) if-equal)]
     ['cons? (type-pred ptr-mask type-cons)]
diff --git a/iniquity/compile-ops.rkt b/iniquity/compile-ops.rkt
index 90bba9b..7163b5f 100644
--- a/iniquity/compile-ops.rkt
+++ b/iniquity/compile-ops.rkt
@@ -65,16 +65,13 @@
           (Add rbx 8))]
     ['unbox
      (seq (assert-box rax)
-          (Xor rax type-box)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-box))))]
     ['car
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 8)))]
+          (Mov rax (Offset rax (- 8 type-cons))))]
     ['cdr
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-cons))))]
 
     ['empty? (seq (Cmp rax (value->bits '())) if-equal)]
     ['cons? (type-pred ptr-mask type-cons)]
@@ -85,10 +82,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-vector rax)
-            (Xor rax type-vect)
-            (Cmp rax 0)
+            (Cmp rax type-vect)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-vect)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
@@ -98,10 +94,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-string rax)
-            (Xor rax type-str)
-            (Cmp rax 0)
+            (Cmp rax type-str)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-str)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
diff --git a/jig/compile-ops.rkt b/jig/compile-ops.rkt
index 90bba9b..7163b5f 100644
--- a/jig/compile-ops.rkt
+++ b/jig/compile-ops.rkt
@@ -65,16 +65,13 @@
           (Add rbx 8))]
     ['unbox
      (seq (assert-box rax)
-          (Xor rax type-box)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-box))))]
     ['car
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 8)))]
+          (Mov rax (Offset rax (- 8 type-cons))))]
     ['cdr
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-cons))))]
 
     ['empty? (seq (Cmp rax (value->bits '())) if-equal)]
     ['cons? (type-pred ptr-mask type-cons)]
@@ -85,10 +82,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-vector rax)
-            (Xor rax type-vect)
-            (Cmp rax 0)
+            (Cmp rax type-vect)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-vect)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
@@ -98,10 +94,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-string rax)
-            (Xor rax type-str)
-            (Cmp rax 0)
+            (Cmp rax type-str)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-str)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
diff --git a/knock/compile-ops.rkt b/knock/compile-ops.rkt
index 90bba9b..7163b5f 100644
--- a/knock/compile-ops.rkt
+++ b/knock/compile-ops.rkt
@@ -65,16 +65,13 @@
           (Add rbx 8))]
     ['unbox
      (seq (assert-box rax)
-          (Xor rax type-box)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-box))))]
     ['car
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 8)))]
+          (Mov rax (Offset rax (- 8 type-cons))))]
     ['cdr
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-cons))))]
 
     ['empty? (seq (Cmp rax (value->bits '())) if-equal)]
     ['cons? (type-pred ptr-mask type-cons)]
@@ -85,10 +82,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-vector rax)
-            (Xor rax type-vect)
-            (Cmp rax 0)
+            (Cmp rax type-vect)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-vect)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
@@ -98,10 +94,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-string rax)
-            (Xor rax type-str)
-            (Cmp rax 0)
+            (Cmp rax type-str)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-str)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
diff --git a/knock/compile.rkt b/knock/compile.rkt
index 3767728..9edcbbf 100644
--- a/knock/compile.rkt
+++ b/knock/compile.rkt
@@ -3,7 +3,8 @@
          compile-e
          compile-es
          compile-define
-         compile-match)
+         compile-match
+         compile-match-clause)
 
 (require "ast.rkt")
 (require "compile-ops.rkt")
@@ -269,8 +270,7 @@
                 (Add rsp (* 8 (length cm))) ; haven't pushed anything yet
                 (Jmp next)
                 (Label ok)
-                (Xor rax type-box)
-                (Mov rax (Offset rax 0))
+                (Mov rax (Offset rax (- type-box)))
                 i1)
            cm1))])]
     [(Cons p1 p2)
diff --git a/loot/compile-ops.rkt b/loot/compile-ops.rkt
index 00388e0..76340c0 100644
--- a/loot/compile-ops.rkt
+++ b/loot/compile-ops.rkt
@@ -65,16 +65,13 @@
           (Add rbx 8))]
     ['unbox
      (seq (assert-box rax)
-          (Xor rax type-box)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-box))))]
     ['car
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 8)))]
+          (Mov rax (Offset rax (- 8 type-cons))))]
     ['cdr
      (seq (assert-cons rax)
-          (Xor rax type-cons)
-          (Mov rax (Offset rax 0)))]
+          (Mov rax (Offset rax (- type-cons))))]
 
     ['empty? (seq (Cmp rax (value->bits '())) if-equal)]
     ['cons? (type-pred ptr-mask type-cons)]
@@ -85,10 +82,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-vector rax)
-            (Xor rax type-vect)
-            (Cmp rax 0)
+            (Cmp rax type-vect)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-vect)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
@@ -98,10 +94,9 @@
      (let ((zero (gensym))
            (done (gensym)))
        (seq (assert-string rax)
-            (Xor rax type-str)
-            (Cmp rax 0)
+            (Cmp rax type-str)
             (Je zero)
-            (Mov rax (Offset rax 0))
+            (Mov rax (Offset rax (- type-str)))
             (Sal rax int-shift)
             (Jmp done)
             (Label zero)
diff --git a/loot/compile.rkt b/loot/compile.rkt
index 4fc95d0..a8a1a82 100644
--- a/loot/compile.rkt
+++ b/loot/compile.rkt
@@ -4,6 +4,7 @@
          compile-es
          compile-define
          compile-match
+         compile-match-clause
          compile-lambda-define
          copy-env-to-stack
          free-vars-to-heap)
@@ -85,7 +86,6 @@
        (let ((env  (append (reverse fvs) (reverse xs) (list #f))))
          (seq (Label (symbol->label f))
               (Mov rax (Offset rsp (* 8 (length xs))))
-              (Xor rax type-proc)
               (copy-env-to-stack fvs 8)
               (compile-e e env #t)
               (Add rsp (* 8 (length env))) ; pop env
@@ -97,7 +97,7 @@
   (match fvs
     ['() (seq)]
     [(cons _ fvs)
-     (seq (Mov r9 (Offset rax off))
+     (seq (Mov r9 (Offset rax (- off type-proc)))
           (Push r9)
           (copy-env-to-stack fvs (+ 8 off)))]))
 
@@ -218,8 +218,7 @@
        (Add rsp (* 8 (length c)))
        (Mov rax (Offset rsp (* 8 (length es))))
        (assert-proc rax)
-       (Xor rax type-proc)
-       (Mov rax (Offset rax 0))
+       (Mov rax (Offset rax (- type-proc)))
        (Jmp rax)))
 
 ;; Integer Integer -> Asm
@@ -242,8 +241,7 @@
          (compile-es (cons e es) (cons #f c))
          (Mov rax (Offset rsp i))
          (assert-proc rax)
-         (Xor rax type-proc)
-         (Mov rax (Offset rax 0)) ; fetch the code label
+         (Mov rax (Offset rax (- type-proc))) ; fetch the code label
          (Jmp rax)
          (Label r))))
 
@@ -386,8 +384,7 @@
                 (Add rsp (* 8 (length cm))) ; haven't pushed anything yet
                 (Jmp next)
                 (Label ok)
-                (Xor rax type-box)
-                (Mov rax (Offset rax 0))
+                (Mov rax (Offset rax (- type-box)))
                 i1)
            cm1))])]
     [(Cons p1 p2)