diff --git a/src/program_builder.cc b/src/program_builder.cc
index 11b960d5b7..bee3f299bb 100644
--- a/src/program_builder.cc
+++ b/src/program_builder.cc
@@ -28,11 +28,10 @@
 namespace tint {
 
 ProgramBuilder::ProgramBuilder()
-    : ty(this), ast_(ast_nodes_.Create<ast::Module>(Source{})) {}
+    : ast_(ast_nodes_.Create<ast::Module>(Source{})) {}
 
 ProgramBuilder::ProgramBuilder(ProgramBuilder&& rhs)
-    : ty(std::move(rhs.ty)),
-      types_(std::move(rhs.types_)),
+    : types_(std::move(rhs.types_)),
       ast_nodes_(std::move(rhs.ast_nodes_)),
       sem_nodes_(std::move(rhs.sem_nodes_)),
       ast_(rhs.ast_),
@@ -46,7 +45,6 @@ ProgramBuilder::~ProgramBuilder() = default;
 ProgramBuilder& ProgramBuilder::operator=(ProgramBuilder&& rhs) {
   rhs.MarkAsMoved();
   AssertNotMoved();
-  ty = std::move(rhs.ty);
   types_ = std::move(rhs.types_);
   ast_nodes_ = std::move(rhs.ast_nodes_);
   sem_nodes_ = std::move(rhs.sem_nodes_);
diff --git a/src/program_builder.h b/src/program_builder.h
index f0ecfb3471..24a018640a 100644
--- a/src/program_builder.h
+++ b/src/program_builder.h
@@ -477,7 +477,7 @@ class ProgramBuilder {
     template <typename T>
     struct CToAST {};
 
-    ProgramBuilder* builder;
+    ProgramBuilder* const builder;
   };
 
   //////////////////////////////////////////////////////////////////////////////
@@ -1101,7 +1101,7 @@ class ProgramBuilder {
   void WrapInFunction(ast::StatementList stmts);
 
   /// The builder types
-  TypesBuilder ty;
+  TypesBuilder const ty{this};
 
  protected:
   /// Asserts that the builder has not been moved.