Index: /trunk/source/compiler/ARM/arm-asm.lisp
===================================================================
--- /trunk/source/compiler/ARM/arm-asm.lisp	(revision 15118)
+++ /trunk/source/compiler/ARM/arm-asm.lisp	(revision 15119)
@@ -1182,4 +1182,7 @@
                (ecase (car count)
                  (:$ (destructuring-bind (countval) (cdr count)
+                       (if (and (eql (logand (eval countval) 31) 0)
+                                (eq op :ror))
+                         (error "Invalid shift count for :ROR : ~s." countval))
                        (set-field-value instruction (byte 12 0)
                                         (logior (need-arm-gpr reg)