diff --git a/src/new-cmp/cmpc-top.lsp b/src/new-cmp/cmpc-top.lsp
index e340ad063..52a324406 100644
--- a/src/new-cmp/cmpc-top.lsp
+++ b/src/new-cmp/cmpc-top.lsp
@@ -15,7 +15,7 @@
 (in-package "C-BACKEND")
 
 (defun ctop-write (name h-pathname data-pathname
-                   &key shared-data
+                   &key shared-data input-designator
                    &aux def top-output-string
                    (*volatile* "volatile "))
 
@@ -31,7 +31,8 @@
                    year month day hour minute)
     (wt-comment-nl "Machine: ~A ~A ~A"
                    (software-type) (software-version) (machine-type)))
-  (wt-comment-nl "Source: ~A" input-designator)
+  (wt-comment-nl "Source: ~A"
+                 (or input-designator "Uknown"))
 
   (wt-nl1 "#include " c::*cmpinclude*)
   (wt-nl1 "#include \"" (si::coerce-to-filename h-pathname) "\"")
diff --git a/src/new-cmp/cmpmain.lsp b/src/new-cmp/cmpmain.lsp
index 8c11272a2..86b31f877 100644
--- a/src/new-cmp/cmpmain.lsp
+++ b/src/new-cmp/cmpmain.lsp
@@ -811,6 +811,7 @@ from the C language code.  NIL means \"do not create the file\"."
       (catch *cmperr-tag* (c-backend::ctop-write init-name
                                                  h-pathname
                                                  data-pathname
+                                                 :input-designator input-designator
                                                  :shared-data shared-data))
       (terpri *compiler-output1*)
       (terpri *compiler-output2*))))