diff --git a/lib/core.fs b/lib/core.fs
index cfa6e6d..abc4968 100644
--- a/lib/core.fs
+++ b/lib/core.fs
@@ -1,9 +1,6 @@
 \ planckforth -
 \ Copyright (C) 2021 nineties
 
-\ test/tester.fs and test codes are base on
-\ https://github.com/gerryjackson/forth2012-test-suite
-
 defined? roll [unless]
     : roll ( wn ... w1 n -- w1 wn ... w2 -- )
         dup 0<= if drop else swap >r 1- recurse r> swap then
diff --git a/lib/tester.fs b/lib/tester.fs
index bb24441..f65384a 100644
--- a/lib/tester.fs
+++ b/lib/tester.fs
@@ -1,6 +1,9 @@
 \ planckforth -
 \ Copyright (C) 2021 nineties
 
+\ test/tester.fs and test codes are base on
+\ https://github.com/gerryjackson/forth2012-test-suite
+
 variable verbose
 \ true verbose !
 false verbose !