diff --git a/src/interpreter/environment.rs b/src/interpreter/environment.rs
index 97e1e46..824bf50 100644
--- a/src/interpreter/environment.rs
+++ b/src/interpreter/environment.rs
@@ -5,7 +5,10 @@ use crate::{
     tokens::Token,
 };
 
-use super::{Value, native_fn::{self, NativeFunction}};
+use super::{
+    native_fn::{self, NativeFunction},
+    Value,
+};
 
 /// A mutable reference to an environment.
 pub(super) type EnvironmentRef = Rc<RefCell<Environment>>;
@@ -127,7 +130,7 @@ impl Environment {
     pub fn read(&self, name: &str) -> Value {
         match self.values.get(name) {
             Some(Some(v)) => v.clone(),
-            _ => panic!("Symbol {name} does not exist"),
+            _ => panic!("Symbol {name} does not exist ({:?})", self.values.keys()),
         }
     }
 
diff --git a/src/interpreter/functions.rs b/src/interpreter/functions.rs
index 7fd07dc..b58d866 100644
--- a/src/interpreter/functions.rs
+++ b/src/interpreter/functions.rs
@@ -77,13 +77,13 @@ impl Callable for Function {
                 InterpreterFlowControl::Result(_) => (),
                 InterpreterFlowControl::Return(v) if !self.is_initializer => return Ok(v),
                 InterpreterFlowControl::Return(_) => {
-                    return Ok(itpr_state.environment.borrow().read("this"))
+                    return Ok(self.env.borrow().read("this"))
                 }
                 _ => panic!("unexpected flow control {:?}", result),
             }
         }
         if self.is_initializer {
-            Ok(itpr_state.environment.borrow().read("this"))
+            Ok(self.env.borrow().read("this"))
         } else {
             Ok(Value::Nil)
         }