diff --git a/src/main/scala/inox/ast/Definitions.scala b/src/main/scala/inox/ast/Definitions.scala
index e29fa276294f2eb61c43716fb0eca0bf5e740b31..4559bc702e87d74a2d5de569167b7106048168a6 100644
--- a/src/main/scala/inox/ast/Definitions.scala
+++ b/src/main/scala/inox/ast/Definitions.scala
@@ -84,7 +84,7 @@ trait Definitions { self: Trees =>
 
   /** A wrapper for a program. For now a program is simply a single object. */
   trait AbstractSymbols
-     extends Tree
+     extends Printable
         with TypeOps
         with SymbolOps
         with CallGraph