diff --git a/artiq/compiler/ir.py b/artiq/compiler/ir.py
index 86af6062c..cc8fda5cc 100644
--- a/artiq/compiler/ir.py
+++ b/artiq/compiler/ir.py
@@ -344,14 +344,13 @@ class Argument(NamedValue):
     def __str__(self):
         return self.as_operand()
 
-class Function(Value):
+class Function:
     """
     A function containing SSA IR.
     """
 
     def __init__(self, typ, name, arguments):
-        super().__init__(typ)
-        self.name = name
+        self.type, self.name = typ, name
         self.names, self.arguments, self.basic_blocks = set(), [], []
         self.set_arguments(arguments)
 
@@ -389,10 +388,6 @@ class Function(Value):
         return [block for block in self.basic_blocks
                        if block.is_terminated() and successor in block.successors()]
 
-    def as_operand(self):
-        return "{} @{}".format(types.TypePrinter().name(self.type),
-                               escape_name(self.name))
-
     def __str__(self):
         printer = types.TypePrinter()
         lines = []
@@ -766,6 +761,30 @@ class Builtin(Instruction):
     def opcode(self):
         return "builtin({})".format(self.op)
 
+class Closure(Instruction):
+    """
+    A closure creation operation.
+
+    :ivar target_function: (:class:`Function`) function to invoke
+    """
+
+    """
+    :param func: (:class:`Function`) function
+    :param env: (:class:`Value`) outer environment
+    """
+    def __init__(self, func, env, name=""):
+        assert isinstance(func, Function)
+        assert isinstance(env, Value)
+        assert is_environment(env.type)
+        super().__init__([env], func.type, name)
+        self.target_function = func
+
+    def opcode(self):
+        return "closure({})".format(self.target_function.name)
+
+    def get_environment(self):
+        return self.operands[0]
+
 class Call(Instruction):
     """
     A function call operation.
@@ -776,7 +795,6 @@ class Call(Instruction):
     :param args: (list of :class:`Value`) function arguments
     """
     def __init__(self, func, args, name=""):
-        print(func)
         assert isinstance(func, Value)
         for arg in args: assert isinstance(arg, Value)
         super().__init__([func] + args, func.type.ret, name)
diff --git a/artiq/compiler/transforms/ir_generator.py b/artiq/compiler/transforms/ir_generator.py
index 834aed7ff..3edb90160 100644
--- a/artiq/compiler/transforms/ir_generator.py
+++ b/artiq/compiler/transforms/ir_generator.py
@@ -131,7 +131,8 @@ class IRGenerator(algorithm.Visitor):
             env = self.append(ir.Alloc([], ir.TEnvironment(node.typing_env), name="env"))
             old_env, self.current_env = self.current_env, env
 
-            priv_env = self.append(ir.Alloc([], ir.TEnvironment({ ".return": typ.ret })))
+            priv_env = self.append(ir.Alloc([], ir.TEnvironment({ ".return": typ.ret }),
+                                            name="privenv"))
             old_priv_env, self.current_private_env = self.current_private_env, priv_env
 
             self.generic_visit(node)
@@ -193,7 +194,8 @@ class IRGenerator(algorithm.Visitor):
             old_env, self.current_env = self.current_env, env
 
             if not is_lambda:
-                priv_env = self.append(ir.Alloc([], ir.TEnvironment({ ".return": typ.ret })))
+                priv_env = self.append(ir.Alloc([], ir.TEnvironment({ ".return": typ.ret }),
+                                                name="privenv"))
                 old_priv_env, self.current_private_env = self.current_private_env, priv_env
 
             self.append(ir.SetLocal(env, ".outer", env_arg))
@@ -215,8 +217,6 @@ class IRGenerator(algorithm.Visitor):
             else:
                 if not self.current_block.is_terminated():
                     self.current_block.append(ir.Unreachable())
-
-            return func
         finally:
             self.name = old_name
             self.current_function = old_func
@@ -226,6 +226,8 @@ class IRGenerator(algorithm.Visitor):
             if not is_lambda:
                 self.current_private_env = old_priv_env
 
+        return self.append(ir.Closure(func, self.current_env))
+
     def visit_FunctionDefT(self, node):
         func = self.visit_function(node, is_lambda=False)
         self._set_local(node.name, func)