diff --git a/src/quick-lint-js/diag/diag-list.cpp b/src/quick-lint-js/diag/diag-list.cpp
index 37aa0d961..a8613c0ab 100644
--- a/src/quick-lint-js/diag/diag-list.cpp
+++ b/src/quick-lint-js/diag/diag-list.cpp
@@ -81,7 +81,8 @@ Span_Size Diag_List::size() const {
 }
 
 bool Diag_List::reported_any_diagnostic_except_since(
-    std::initializer_list<Diag_Type> ignored_types, const Rewind_State &r) {
+    std::initializer_list<Diag_Type> ignored_types,
+    const Rewind_State &r) const {
   for (Node_Base *node = r.last_ == nullptr ? this->first_ : r.last_;
        node != nullptr; node = node->next) {
     if (!contains(ignored_types, node->type)) {
diff --git a/src/quick-lint-js/diag/diag-list.h b/src/quick-lint-js/diag/diag-list.h
index 7d9a3e36f..2e1d52535 100644
--- a/src/quick-lint-js/diag/diag-list.h
+++ b/src/quick-lint-js/diag/diag-list.h
@@ -70,7 +70,8 @@ class Diag_List {
   Span_Size size() const;
 
   bool reported_any_diagnostic_except_since(
-      std::initializer_list<Diag_Type> ignored_types, const Rewind_State &);
+      std::initializer_list<Diag_Type> ignored_types,
+      const Rewind_State &) const;
   bool have_diagnostic(Diag_Type type) const;
 
   // Removes all diagnostics, but does not deallocate memory.
diff --git a/src/quick-lint-js/fe/lex.cpp b/src/quick-lint-js/fe/lex.cpp
index d06199af2..14f738565 100644
--- a/src/quick-lint-js/fe/lex.cpp
+++ b/src/quick-lint-js/fe/lex.cpp
@@ -1252,7 +1252,7 @@ void Lexer::roll_back_transaction(Lexer_Transaction&& transaction) {
   this->last_last_token_end_ = transaction.old_last_last_token_end;
   this->input_ = transaction.old_input;
 
-  this->diag_list_.diags().rewind(std::move(transaction.diag_list_rewind));
+  this->diags_.rewind(std::move(transaction.diag_list_rewind));
 }
 
 bool Lexer::transaction_has_lex_diagnostics(const Lexer_Transaction& transaction) const {
diff --git a/src/quick-lint-js/fe/lex.h b/src/quick-lint-js/fe/lex.h
index def2d51cc..2428a1755 100644
--- a/src/quick-lint-js/fe/lex.h
+++ b/src/quick-lint-js/fe/lex.h
@@ -144,12 +144,7 @@ class Lexer {
   bool test_for_regexp(const Char8* regexp_begin);
 
   // Returns all the diagnostics reported so far by the the lexer.
-  Diag_List& diags() { return this->diag_list_.diags(); }
-
-  // TODO(#1154): Delete.
-  Diag_List_Diag_Reporter& diag_list_diag_reporter() {
-    return this->diag_list_;
-  }
+  Diag_List& diags() { return this->diags_; }
 
   // Save lexer state.
   //
@@ -348,9 +343,7 @@ class Lexer {
 
   Monotonic_Allocator allocator_{"lexer::allocator_"};
 
-  Diag_List_Diag_Reporter diag_list_ =
-      Diag_List_Diag_Reporter(&this->allocator_);
-  Diag_List& diags_ = diag_list_.diags();
+  Diag_List diags_ = Diag_List(&this->allocator_);
 
   friend struct Lex_Tables;
 };