diff --git a/racket/src/racket/src/jitcommon.c b/racket/src/racket/src/jitcommon.c
index 665ff8b904..cfc53e8473 100644
--- a/racket/src/racket/src/jitcommon.c
+++ b/racket/src/racket/src/jitcommon.c
@@ -2591,8 +2591,7 @@ static int common6(mz_jit_state *jitter, void *_data)
     CHECK_LIMIT();
     
     jit_andi_l(JIT_V1, JIT_R2, SCHEME_MARK_SEGMENT_MASK);
-    jit_movi_l(JIT_R1, sizeof(Scheme_Cont_Mark));
-    jit_mulr_l(JIT_V1, JIT_V1, JIT_R1);
+    jit_lshi_l(JIT_V1, JIT_V1, LOG_CONT_MARK_WORD_COUNT+JIT_LOG_WORD_SIZE);
     jit_addr_l(JIT_R0, JIT_R0, JIT_V1);
     CHECK_LIMIT();
     /* R0 now points to the right record */
@@ -2649,8 +2648,7 @@ static int common6(mz_jit_state *jitter, void *_data)
     /* R0 now points to the right array */
     
     jit_andi_l(JIT_V1, JIT_R2, SCHEME_MARK_SEGMENT_MASK);
-    jit_movi_l(JIT_R1, sizeof(Scheme_Cont_Mark));
-    jit_mulr_l(JIT_V1, JIT_V1, JIT_R1);
+    jit_lshi_l(JIT_V1, JIT_V1, LOG_CONT_MARK_WORD_COUNT+JIT_LOG_WORD_SIZE);
     jit_addr_l(JIT_R0, JIT_R0, JIT_V1);
     CHECK_LIMIT();
     /* R0 now points to the right record */
diff --git a/racket/src/racket/src/schpriv.h b/racket/src/racket/src/schpriv.h
index d477767b74..8f5e2c62fb 100644
--- a/racket/src/racket/src/schpriv.h
+++ b/racket/src/racket/src/schpriv.h
@@ -1687,6 +1687,7 @@ typedef struct Scheme_Cont_Mark {
   Scheme_Object *cache; /* chain and/or shortcut */
   MZ_MARK_POS_TYPE pos; /* Odd numbers - so they look like non-pointers */
 } Scheme_Cont_Mark;
+#define LOG_CONT_MARK_WORD_COUNT 2
 
 void scheme_new_mark_segment(Scheme_Thread *p);