diff --git a/tst/testinstall/syntaxtree.tst b/tst/testinstall/syntaxtree.tst
index 2307e39559..9d654ce5cb 100644
--- a/tst/testinstall/syntaxtree.tst
+++ b/tst/testinstall/syntaxtree.tst
@@ -10,6 +10,13 @@ gap> SyntaxTree(x -> x);
 <syntax tree>
 gap> SyntaxTree(\+);
 Error, SYNTAX_TREE: <func> must be a plain GAP function (not a function)
+gap> test_tree := function( f )
+>       local curr_tree, new_func, new_tree;
+>       curr_tree := SYNTAX_TREE( f );
+>       new_func := SYNTAX_TREE_CODE( curr_tree );
+>       new_tree := SYNTAX_TREE( new_func );
+>       return new_tree = curr_tree;
+> end;;
 
 # Just try compiling all functions we can find in the workspace
 # to see nothing crashes.
@@ -37,8 +44,7 @@ gap> testit := function(f)
 >   local tree;
 >   tree := SYNTAX_TREE(f);
 >   Display(tree);
->   # TODO: recode the tree, then decode again and compare
->   return true;
+>   return test_tree( f );
 > end;;
 
 # T_PROCCALL_0ARGS