diff --git a/builtins/read.def b/builtins/read.def
index 5135e2b1..854b7b8f 100644
--- a/builtins/read.def
+++ b/builtins/read.def
@@ -788,8 +788,11 @@ read_builtin (WORD_LIST *list)
 	  char *x;
 	  x = (char *)xrealloc (input_string, size += 128);
 
-	  /* Only need to change unwind-protect if input_string changes */
+#if 0
+	  /* This is, in theory, undefined behavior, since input_string may
+	     have been freed. */
 	  if (x != input_string)
+#endif
 	    {
 	      input_string = x;
 	      remove_unwind_protect ();
diff --git a/patchlevel.h b/patchlevel.h
index 8020b323..492f98f7 100644
--- a/patchlevel.h
+++ b/patchlevel.h
@@ -25,6 +25,6 @@
    regexp `^#define[ 	]*PATCHLEVEL', since that's what support/mkversion.sh
    looks for to find the patch level (for the sccs version string). */
 
-#define PATCHLEVEL 12
+#define PATCHLEVEL 13
 
 #endif /* _PATCHLEVEL_H_ */