diff --git a/interp.py b/interp.py
index f57cfc8..79944e1 100644
--- a/interp.py
+++ b/interp.py
@@ -25,49 +25,52 @@
         return Text(input())
 
 class Interpreter:
-    def resolve_value(self, env, value):
+    def __init__(self, env):
+        self.env = env
+
+    def resolve_value(self, value):
         if value.__class__ == ast_types.Reference:
-            return env[value.value]
+            return self.env[value.value]
         elif value.__class__ == ast_types.Text:
             return Text(value.value)
         else:
             print("Unimplemented value: %s" % (value))
 
-    def run_statement(self, env, ast):
-        subject = self.resolve_value(env, ast.subject)
+    def run_statement(self, ast):
+        subject = self.resolve_value(ast.subject)
         if ast.verb == None:
             return subject
         args = []
         for arg in ast.arguments:
-            args.append(self.resolve_value(env, arg))
+            args.append(self.resolve_value(arg))
         return getattr(subject, "verb_" + ast.verb)(args)
 
-    def run_set(self, env, ast):
-        env[ast.subject] = self.run_statement(env, ast.statement)
-        return env[ast.subject]
+    def run_set(self, ast):
+        self.env[ast.subject] = self.run_statement(ast.statement)
+        return self.env[ast.subject]
 
-    def run_conditional(self, env, ast):
+    def run_conditional(self, ast):
         print("Unimplemented if")
         return None
 
-    def run_command(self, env, ast):
+    def run_command(self, ast):
         if ast.__class__ == ast_types.Statement:
-            return self.run_statement(env, ast)
+            return self.run_statement(ast)
         elif ast.__class__ == ast_types.Set:
-            return self.run_set(env, ast)
+            return self.run_set(ast)
         elif ast.__class__ == ast_types.Conditional:
-            return self.run_conditional(env, ast)
+            return self.run_conditional(ast)
         else:
             print("Unknown command %s" % (ast))
             return None
 
-    def run(self, env, ast):
+    def run(self, ast):
         for command in ast:
-            self.run_command(env, command)
+            self.run_command(command)
         return None
 
 def run_ast(ast):
     env = {
         "System": Module_System(),
     }
-    return Interpreter().run(env, ast)
+    return Interpreter(env).run(ast)