diff --git a/interpreter/Tokenizer.py b/interpreter/Tokenizer.py
index 4fb208a..4a0d148 100644
--- a/interpreter/Tokenizer.py
+++ b/interpreter/Tokenizer.py
@@ -16,6 +16,7 @@ class Tokenizer:
             self.source_text = f.read()
         self.source_index = 0
         self.line_number = 1
+        self.column_number = 0
 
         self.source_text = re.sub("(private)|(public)|(protected)", "", self.source_text)
 
@@ -37,7 +38,7 @@ class Tokenizer:
 
             token = self._get_token(char)
             logging.debug(f"found token \"{token}\" on line {self.line_number}")
-            tokens.append(make_token(token, SourceLocation(self._filename, self.line_number), self.type_name_pattern))
+            tokens.append(make_token(token, SourceLocation(self._filename, self.line_number, self.column_number), self.type_name_pattern))
 
         return tokens
 
@@ -78,8 +79,10 @@ class Tokenizer:
 
         if char == '\n':
             self.line_number += 1
+            self.column_number = 1
 
         self.source_index += 1
+        self.column_number += 1
         return char
 
     def _consume_multiline_comment(self):
diff --git a/interpreter/_token.py b/interpreter/_token.py
index 1fad304..ef8aab7 100644
--- a/interpreter/_token.py
+++ b/interpreter/_token.py
@@ -1,6 +1,5 @@
 """Private definitions for Token class used by the Lexer"""
 
-import logging
 import re
 
 from enum import IntEnum
@@ -12,7 +11,7 @@ STRING_LITERAL_PATTERN = re.compile(r"""('|\")(.*)(\"|')""")
 MATH_OP_PATTERN = re.compile(r"""\+|-|\*|/|<|>""")
 
 class Token_type(IntEnum):
-    UNKNOWN=-1 #maybe this should be renamed to IDENTIFIERs
+    UNKNOWN=-1 #maybe this should be renamed to IDENTIFIER
     LEFT_PAREN=0,
     RIGTH_PAREN=1,
     LEFT_CURLY=2,
@@ -34,15 +33,22 @@ class Token_type(IntEnum):
     TYPE_NAME=18
 
 class SourceLocation:
-    def __init__(self, filename: str, line: int) -> None:
+
+    __slots__ = ["filename", "line", "column"]
+
+    def __init__(self, filename: str, line: int, column: int) -> None:
         self.filename = filename
         self.line = line
+        self.column = column
 
     def __str__(self) -> str:
-        return f"File {self.filename}, line {self.line}"
+        return f"File {self.filename}, {self.line}:{self.column}"
 
 class Token:
-    def __init__(self, type: Token_type, location: SourceLocation, content: Union[str, None]=None) -> None:
+
+    __slots__ = ["type", "content", "location"]
+
+    def __init__(self, type: Token_type, location: SourceLocation, content: str) -> None:
         self.type = type
         self.content = content
         self.location = location
@@ -53,6 +59,7 @@ class Token:
         return f"{self.type}"
 
 def make_token(tag: str, location: SourceLocation, type_name_pattern:re.Pattern) -> Token:
+    """Construct a token object with the provided tag and source location"""
     if tag == '(':
         return Token(Token_type.LEFT_PAREN, location, tag)
     elif tag == ')':