diff --git a/src/alloc.c b/src/alloc.c
index 980085d3292..9feca7ae024 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -5275,7 +5275,8 @@ valid_lisp_object_p (Lisp_Object obj)
       if (valid <= 0)
 	return valid;
 
-      if (SUBRP (obj))
+      /* Strings and conses produced by AUTO_STRING etc. all get here.  */
+      if (SUBRP (obj) || STRINGP (obj) || CONSP (obj))
 	return 1;
 
       return 0;