diff --git a/tests/generators/functions.xml b/tests/generators/functions.xml
index b189ed355..a3489325d 100644
--- a/tests/generators/functions.xml
+++ b/tests/generators/functions.xml
@@ -1,4 +1,5 @@
 <xml xmlns="http://www.w3.org/1999/xhtml">
+  <!-- Do not include <variables> here to test backward compatibility. -->
   <block type="unittest_main" x="0" y="1">
     <statement name="DO">
       <block type="procedures_callnoreturn">
diff --git a/tests/generators/variables.xml b/tests/generators/variables.xml
index a11d0a01a..a3e5848a4 100644
--- a/tests/generators/variables.xml
+++ b/tests/generators/variables.xml
@@ -1,4 +1,5 @@
 <xml xmlns="http://www.w3.org/1999/xhtml">
+  <!-- Do not include <variables> here to test backward compatibility. -->
   <block type="unittest_main" x="0" y="0">
     <statement name="DO">
       <block type="variables_set" inline="false">