diff --git a/src/rstd/collections/stack.rs b/src/rstd/collections/stack.rs
index 63cfdd6..51e7dd0 100644
--- a/src/rstd/collections/stack.rs
+++ b/src/rstd/collections/stack.rs
@@ -6,7 +6,7 @@ use crate::rstd::external_points::*;
 use crate::rstd::{inlining::*, nullable::*, point::*, *};
 
 /// Node containing a (nullable) reference to the next node and an element.
-pub struct StackNode<'a, Ctx: Context<'a>, A: StackCompatible<'a, Ctx>> {
+pub struct StackNode<'a, Ctx: Context<'a>, A: MentionableBase<'a, Ctx>> {
     /// Reference comes first due to being inlineable.
     pub rest: Stack<'a, Ctx, A>,
     /// Unlike the original implementation in Python, doesn't default to using Point.
@@ -29,7 +29,7 @@ impl<F> StackNodeFactory<F> {
     }
 }
 
-impl<'a, Ctx: Context<'a>, A: StackCompatible<'a, Ctx>> Serializable for StackNode<'a, Ctx, A> {
+impl<'a, Ctx: Context<'a>, A: MentionableBase<'a, Ctx>> Serializable for StackNode<'a, Ctx, A> {
     fn serialize(&self, serializer: &mut dyn Serializer) {
         self.rest.serialize(serializer);
         self.element.serialize(serializer);
@@ -90,7 +90,7 @@ where
     }
 }
 
-impl<'a, Ctx: Context<'a>, A: StackCompatible<'a, Ctx>> MentionableBase<'a, Ctx>
+impl<'a, Ctx: Context<'a>, A: MentionableBase<'a, Ctx>> MentionableBase<'a, Ctx>
     for StackNode<'a, Ctx, A>
 {
     type Fctr = StackNodeFactory<A::Fctr>;
@@ -148,10 +148,7 @@ impl<F> StackNodeFactory<F> {
     }
 }
 
-impl<'a, Ctx: Context<'a>, F: Factory<'a, Ctx>> FactoryBase<'a, Ctx> for StackNodeFactory<F>
-where
-    F::Mtbl: StackCompatible<'a, Ctx>,
-{
+impl<'a, Ctx: Context<'a>, F: FactoryBase<'a, Ctx>> FactoryBase<'a, Ctx> for StackNodeFactory<F> {
     type Mtbl = StackNode<'a, Ctx, F::Mtbl>;
 
     type ParseError = StackParseError<ParseError<'a, Ctx, F>>;