diff --git a/src/lsp/arraylib.lsp b/src/lsp/arraylib.lsp
index 331a1fcca..8d4807aae 100644
--- a/src/lsp/arraylib.lsp
+++ b/src/lsp/arraylib.lsp
@@ -136,7 +136,7 @@ INDEXes must be equal to the rank of ARRAY."
     (do* ((r (array-rank array))
           (i 0 (1+ i))
           (j 0)
-          (s indices (cdr (truly-the cons s))))
+          (s indices (cons-cdr s)))
          ((null s)
           (when (< i r)
             (indexing-error array indices))
@@ -144,7 +144,7 @@ INDEXes must be equal to the rank of ARRAY."
       (declare (ext:array-index j)
                (fixnum i r))
       (let* ((d (array-dimension array i))
-             (o (car (truly-the cons s)))
+             (o (cons-car s))
              ndx)
         (declare (ext:array-index ndx))
         (unless (and (typep o 'fixnum)