--- a/src/compiler/alpha/array.lisp
+++ b/src/compiler/alpha/array.lisp
@@ -311,7 +311,7 @@
   (def-full-data-vector-frobs simple-vector *
     descriptor-reg any-reg null zero)
   
-  (def-partial-data-vector-frobs simple-string base-char :byte nil
+  (def-partial-data-vector-frobs simple-base-string base-char :byte nil
     base-char-reg)
   
   (def-partial-data-vector-frobs simple-array-unsigned-byte-8 positive-fixnum