diff --git a/src/assembler/session/builder.rs b/src/assembler/session/builder.rs
index c9b88ac..b3199b9 100644
--- a/src/assembler/session/builder.rs
+++ b/src/assembler/session/builder.rs
@@ -55,7 +55,7 @@ impl<C, R, I, D> Backend<R::Span> for CompositeSession<C, R, I, D>
 where
     R: SpanSystem<BufId>,
     I: StringSource,
-    Self: MacroSource + Diagnostics<R::Span>,
+    Self: Diagnostics<R::Span>,
     for<'a> DiagnosticsContext<'a, C, R, D>: Diagnostics<R::Span>,
 {
     fn define_symbol(&mut self, name: SymbolId, _span: R::Span, expr: Expr<SymbolId, R::Span>) {
@@ -133,10 +133,6 @@ where
     }
 }
 
-impl<S: Clone> SymbolSource for ObjectBuilder<S> {
-    type SymbolId = SymbolId;
-}
-
 impl<S: Clone> AllocSymbol<S> for ObjectBuilder<S> {
     fn alloc_symbol(&mut self, _span: S) -> SymbolId {
         self.object.content.symbols.alloc().into()
diff --git a/src/assembler/session/macros.rs b/src/assembler/session/macros.rs
index 010187e..95eb752 100644
--- a/src/assembler/session/macros.rs
+++ b/src/assembler/session/macros.rs
@@ -27,16 +27,7 @@ pub(crate) type VecMacroTable<D, R> = Vec<Rc<MacroDef<D, R>>>;
 
 pub type MacroArgs<T, S> = (Box<[Box<[T]>]>, Box<[Box<[S]>]>);
 
-impl<D, R> MacroSource for VecMacroTable<D, R> {
-    type MacroId = MacroId;
-}
-
-impl<'a, C, R: SpanSystem<BufId>, I: StringSource, D> MacroSource for CompositeSession<C, R, I, D> {
-    type MacroId = MacroId;
-}
-
-impl<C, R, I, D> MacroTable<I::StringRef, <Self as SpanSource>::Span>
-    for CompositeSession<C, R, I, D>
+impl<C, R, I, D> MacroTable<I::StringRef, R::Span> for CompositeSession<C, R, I, D>
 where
     Self: Lex<R, I, Span = R::Span, StringRef = I::StringRef>,
     C: Codebase,
@@ -47,7 +38,6 @@ where
     Self: EmitDiag<R::Span, R::Stripped>,
     Self: StartScope + NameTable<I::StringRef>,
     Self: Backend<R::Span>,
-    Self: MacroSource<MacroId = MacroId>,
     <Self as StringSource>::StringRef: 'static,
     <Self as SpanSource>::Span: 'static,
     <Self as Lex<R, I>>::TokenIter: 'static,
diff --git a/src/assembler/session/mod.rs b/src/assembler/session/mod.rs
index d6cdfb3..845cd60 100644
--- a/src/assembler/session/mod.rs
+++ b/src/assembler/session/mod.rs
@@ -95,14 +95,6 @@ pub trait StringSource {
     type StringRef: Clone + Debug + Eq + Hash;
 }
 
-pub trait SymbolSource {
-    type SymbolId: Clone;
-}
-
-pub(crate) trait MacroSource {
-    type MacroId: Clone;
-}
-
 pub(super) type Session<'a> = CompositeSession<
     FileCodebase<'a, dyn FileSystem>,
     RcContextFactory<BufId>,
@@ -224,10 +216,6 @@ impl<C, R: SpanSystem<BufId>, I: StringSource, D> StringSource for CompositeSess
     type StringRef = I::StringRef;
 }
 
-impl<C, R: SpanSystem<BufId>, I: StringSource, D> SymbolSource for CompositeSession<C, R, I, D> {
-    type SymbolId = SymbolId;
-}
-
 impl<C, R: SpanSystem<BufId>, I: StringSource, D> NextToken for CompositeSession<C, R, I, D> {
     fn next_token(&mut self) -> Option<LexItem<Self::StringRef, Self::Span>> {
         let token = self
@@ -246,7 +234,6 @@ impl<C, R: SpanSystem<BufId>, I: StringSource, D> NextToken for CompositeSession
 impl<C, R: SpanSystem<BufId>, I: StringSource, D> EmitDiag<R::Span, R::Stripped>
     for CompositeSession<C, R, I, D>
 where
-    Self: SymbolSource + MacroSource,
     for<'a> DiagnosticsContext<'a, C, R, D>: EmitDiag<R::Span, R::Stripped>,
     R::Stripped: Clone,
 {