diff --git a/libguile/gc.h b/libguile/gc.h
index 3b0706686..c67edfddf 100644
--- a/libguile/gc.h
+++ b/libguile/gc.h
@@ -86,7 +86,7 @@ typedef scm_cell * SCM_CELLPTR;
  */
 
 #define SCM_VALIDATE_CELL(x) \
-        (SCM_DEBUG_CELL_ACCESSES ? (!scm_cellp (x) ? abort () : 1) : 1)
+        (SCM_DEBUG_CELL_ACCESSES ? (!scm_cellp (x) ? (abort (), 0) : 1) : 1)
 
 #define SCM_CELL_WORD(x, n) \
     ((SCM_VALIDATE_CELL (x)), \
@@ -133,8 +133,8 @@ typedef scm_cell * SCM_CELLPTR;
   (SCM_SETCDR ((x), SCM_PACK (SCM_UNPACK (SCM_CDR (x)) | (y))))
 
 #define SCM_CELL_WORD_LOC(x, n) (&SCM_CELL_WORD (x, n))
-#define SCM_CARLOC(x) (&SCM_CAR (x))
-#define SCM_CDRLOC(x) (&SCM_CDR (x))
+#define SCM_CARLOC(x) (&SCM_PACK (((scm_bits_t *) SCM2PTR (x)) [0]))
+#define SCM_CDRLOC(x) (&SCM_PACK (((scm_bits_t *) SCM2PTR (x)) [1]))
 
 
 /* SCM_PTR_LT and friends define how to compare two SCM_CELLPTRs (which may