diff --git a/string.c b/string.c
index 6482e32c51..4e402d9116 100644
--- a/string.c
+++ b/string.c
@@ -689,7 +689,7 @@ rb_str_resize(VALUE str, long len)
 		return str;
 	    }
 	    ptr = ALLOC_N(char,len+1);
-	    MEMCPY(ptr, RSTRING(str)->ary, char, RSTRING_LEN(str));
+	    MEMCPY(ptr, RSTRING_PTR(str), char, RSTRING_LEN(str));
 	    RSTRING(str)->as.heap.ptr = ptr;
 	    STR_SET_NOEMBED(str);
 	}