diff --git a/smnp/environment/environment.py b/smnp/environment/environment.py
index 0433056..fff3799 100644
--- a/smnp/environment/environment.py
+++ b/smnp/environment/environment.py
@@ -6,13 +6,14 @@ from smnp.type.model import Type
 
 
 class Environment():
-    def __init__(self, scopes, functions, methods):
+    def __init__(self, scopes, functions, methods, source):
         self.scopes = scopes
         self.functions = functions
         self.methods = methods
         self.customFunctions = []
         self.customMethods = []
         self.callStack = []
+        self.source = source
 
     def invokeMethod(self, object, name, args):
         builtinMethodResult = self._invokeBuiltinMethod(object, name, args)
diff --git a/smnp/environment/factory.py b/smnp/environment/factory.py
index ede8e66..32ae6ce 100644
--- a/smnp/environment/factory.py
+++ b/smnp/environment/factory.py
@@ -1,7 +1,3 @@
-from smnp.environment.environment import Environment
-from smnp.module import functions, methods
-
-
 def createEnvironment():
-    return Environment([{}], functions, methods)
+    return
  
diff --git a/smnp/error/base.py b/smnp/error/base.py
index f5413ef..cf593b4 100644
--- a/smnp/error/base.py
+++ b/smnp/error/base.py
@@ -2,6 +2,7 @@ class SmnpException(Exception):
     def __init__(self, msg, pos):
         self.msg = msg
         self.pos = pos
+        self.file = None
 
     def _title(self):
         pass
@@ -10,7 +11,10 @@ class SmnpException(Exception):
         return ""
 
     def _position(self):
-        return "" if self.pos is None else f" [line {self.pos[0]+1}, col {self.pos[1]+1}]"
+        return "" if self.pos is None else f"[line {self.pos[0]+1}, col {self.pos[1]+1}]"
+
+    def _file(self):
+        return "" if self.file is None else f"File: {self.file}"
 
     def message(self):
-        return f"{self._title()}{self._position()}:\n{self.msg}\n{self._postMessage()}"
+        return f"{self._title()}\n{self._file()} {self._position()}\n\n{self.msg}\n{self._postMessage()}"
diff --git a/smnp/error/custom.py b/smnp/error/custom.py
index d9f6def..0b35f50 100644
--- a/smnp/error/custom.py
+++ b/smnp/error/custom.py
@@ -1,9 +1,12 @@
-from smnp.error.base import SmnpException
+from smnp.error.runtime import RuntimeException
 
 
-class CustomException(SmnpException):
+class CustomException(RuntimeException):
     def __init__(self, message, pos):
         super().__init__(message, pos)
 
     def _title(self):
         return "Execution Error"
+
+    def _postMessage(self):
+        return "\n" + self.environment.callStackToString() if len(self.environment.callStack) > 0 else ""
\ No newline at end of file
diff --git a/smnp/library/loader.py b/smnp/library/loader.py
index c40f6f4..bb4e377 100644
--- a/smnp/library/loader.py
+++ b/smnp/library/loader.py
@@ -5,5 +5,5 @@ from smnp.program.interpreter import Interpreter
 
 def loadStandardLibrary():
     mainSource = resource_string('smnp.library.code', 'main.mus').decode("utf-8")
-    env = Interpreter.interpretString(mainSource)
+    env = Interpreter.interpretString(mainSource, "<stdlib>")
     return env
diff --git a/smnp/program/interpreter.py b/smnp/program/interpreter.py
index 7bbe79e..2a6dcc9 100644
--- a/smnp/program/interpreter.py
+++ b/smnp/program/interpreter.py
@@ -1,6 +1,7 @@
 from smnp.ast.parser import parse
-from smnp.environment.factory import createEnvironment
+from smnp.environment.environment import Environment
 from smnp.error.runtime import RuntimeException
+from smnp.module import functions, methods
 from smnp.program.FileReader import readLines
 from smnp.runtime.evaluator import evaluate
 from smnp.token.tokenizer import tokenize
@@ -9,16 +10,31 @@ from smnp.token.tokenizer import tokenize
 class Interpreter:
 
     @staticmethod
-    def interpretString(string, printTokens=False, printAst=False, execute=True, baseEnvironment=None):
-        return Interpreter._interpret(string.splitlines(), printTokens, printAst, execute, baseEnvironment)
+    def interpretString(string, source, printTokens=False, printAst=False, execute=True, baseEnvironment=None):
+        return Interpreter._interpret(
+            string.splitlines(),
+            source,
+            printTokens,
+            printAst,
+            execute,
+            baseEnvironment,
+        )
 
     @staticmethod
-    def interpretFile(file, printTokens=False, printAst=False, execute=True, baseEnvironment=None):
-        return Interpreter._interpret(readLines(file), printTokens, printAst, execute, baseEnvironment)
+    def interpretFile(file, printTokens=False, printAst=False, execute=True, baseEnvironment=None, source=None):
+        return Interpreter._interpret(
+            readLines(file),
+            source if source is not None else file,
+            printTokens,
+            printAst,
+            execute,
+            baseEnvironment,
+        )
 
     @staticmethod
-    def _interpret(lines, printTokens=False, printAst=False, execute=True, baseEnvironment=None):
-        environment = createEnvironment()
+    def _interpret(lines, source, printTokens=False, printAst=False, execute=True, baseEnvironment=None):
+        environment = Environment([{}], functions, methods, source=source)
+
         if baseEnvironment is not None:
             environment.extend(baseEnvironment)
 
@@ -37,4 +53,5 @@ class Interpreter:
             return environment
         except RuntimeException as e:
             e.environment = environment
+            e.file = environment.source
             raise e
\ No newline at end of file