diff --git a/compiler/old-rt/values.lisp b/compiler/old-rt/values.lisp
index 9875b207a1e0dbfa3b182db258db4899efa08b7f..0e857351621dac1dd82e7f8f9a1e15b6b73a8931 100644
--- a/compiler/old-rt/values.lisp
+++ b/compiler/old-rt/values.lisp
@@ -14,7 +14,7 @@
 (in-package 'c)
 
 (define-vop (reset-stack-pointer)
-  (:args (ptr :scs (any-reg)))
+  (:args (ptr :scs (any-reg descriptor-reg)))
   (:generator 1
     (inst lr sp-tn ptr)))