diff --git a/ast.cpp b/ast.cpp
index fb6a288..331687b 100644
--- a/ast.cpp
+++ b/ast.cpp
@@ -3,11 +3,6 @@
 
 namespace dsp {
 
-void ast_printer_t::visit(const unary_t * unary) const
-{
-  parenthesize((unary->oper).lexeme, unary->right);
-}
-
 void ast_printer_t::visit(const binary_t * binary) const
 {
   parenthesize((binary->oper).lexeme, binary->left, binary->right);
@@ -18,11 +13,21 @@ void ast_printer_t::visit(const grouping_t * grouping) const
   parenthesize("grouping", grouping->expr);
 }
 
+void ast_printer_t::visit(const identifier_t * identifier) const
+{
+  parenthesize("identifier", identifier->name.lexeme);
+}
+
 void ast_printer_t::visit(const literal_t * literal) const
 {
   os << std::to_string(literal->value);
 }
 
+void ast_printer_t::visit(const unary_t * unary) const
+{
+  parenthesize((unary->oper).lexeme, unary->right);
+}
+
 void ast_printer_t::parenthesize(const std::string_view s, const expr_t * a) const
 {
   os << '(' << s << ' ';
diff --git a/ast.hpp b/ast.hpp
index be783c0..62faf2f 100644
--- a/ast.hpp
+++ b/ast.hpp
@@ -17,10 +17,11 @@ struct ast_printer_t : visitor_t<void>
 
   std::ostream& os;
 
-  void visit(const unary_t * unary) const;
   void visit(const binary_t * binary) const;
   void visit(const grouping_t * grouping) const;
+  void visit(const identifier_t * identifier) const;
   void visit(const literal_t * literal) const;
+  void visit(const unary_t * unary) const;
 
   void visit(const op::alu_t * alu) const;
   void visit(const op::mov_ram_x_t * mov_ram_x) const;
diff --git a/expr.hpp b/expr.hpp
index 0d8318d..db2becc 100644
--- a/expr.hpp
+++ b/expr.hpp
@@ -44,6 +44,14 @@ struct grouping_t : expr_accept_t<grouping_t>
   const expr_t * expr;
 };
 
+struct identifier_t : expr_accept_t<identifier_t>
+{
+  identifier_t(token_t name)
+    : name(name) {}
+
+  const token_t name;
+};
+
 struct literal_t : expr_accept_t<literal_t>
 {
   literal_t(num_t value)
diff --git a/parser.cpp b/parser.cpp
index 6121e32..f55cd17 100644
--- a/parser.cpp
+++ b/parser.cpp
@@ -150,7 +150,8 @@ expr_t * parser_t::orl()
 
 expr_t * parser_t::primary()
 {
-  if (match(number)) return new literal_t(std::get<num_t>(previous().literal));
+  if      (match(number))     return new literal_t(std::get<num_t>(previous().literal));
+  else if (match(identifier)) return new identifier_t(previous());
 
   if (match(left_paren)) {
     expr_t * expr = expression();
diff --git a/visitable.hpp b/visitable.hpp
index 604628d..95aac25 100644
--- a/visitable.hpp
+++ b/visitable.hpp
@@ -5,9 +5,9 @@ namespace dsp {
 // expressions
 struct binary_t;
 struct grouping_t;
+struct identifier_t;
 struct literal_t;
 struct unary_t;
-struct assign_t;
 
 // instructions
 namespace op {
diff --git a/visitor.hpp b/visitor.hpp
index ccf232c..199a3ee 100644
--- a/visitor.hpp
+++ b/visitor.hpp
@@ -8,10 +8,11 @@ namespace dsp {
 template <typename T>
 struct visitor_t
 {
-  virtual T visit(const unary_t * expr) const = 0;
   virtual T visit(const binary_t * expr) const = 0;
   virtual T visit(const grouping_t * expr) const = 0;
+  virtual T visit(const identifier_t * expr) const = 0;
   virtual T visit(const literal_t * expr) const = 0;
+  virtual T visit(const unary_t * expr) const = 0;
 
   virtual T visit(const op::alu_t * stmt) const = 0;
   virtual T visit(const op::mov_ram_x_t * mov_ram_x) const = 0;