diff --git a/examples/codepage_tables.py b/examples/codepage_tables.py
index 9436910..3053681 100644
--- a/examples/codepage_tables.py
+++ b/examples/codepage_tables.py
@@ -3,8 +3,6 @@
 
 import sys
 
-import six
-
 from escpos import printer
 from escpos.constants import (
     CODEPAGE_CHANGE,
@@ -38,7 +36,7 @@ def print_codepage(printer, codepage):
     """Print a codepage."""
     if codepage.isdigit():
         codepage = int(codepage)
-        printer._raw(CODEPAGE_CHANGE + six.int2byte(codepage))
+        printer._raw(CODEPAGE_CHANGE + bytes((codepage,)))
         printer._raw("after")
     else:
         printer.charcode(codepage)
@@ -58,7 +56,9 @@ def print_codepage(printer, codepage):
         printer.set()
 
         for y in range(0, 16):
-            byte = six.int2byte(x * 16 + y)
+            byte = bytes(
+                (x * 16 + y),
+            )
 
             if byte in (ESC, CTL_LF, CTL_FF, CTL_CR, CTL_HT, CTL_VT):
                 byte = " "
diff --git a/test/test_function_buzzer.py b/test/test_function_buzzer.py
index 85d5cd7..2118cc0 100644
--- a/test/test_function_buzzer.py
+++ b/test/test_function_buzzer.py
@@ -1,14 +1,13 @@
 import pytest
-import six
 
 from escpos import printer
 from escpos.constants import BUZZER
 
 
-def test_buzzer_function_with_default_params():
+def test_buzzer_function_with_default_params() -> None:
     instance = printer.Dummy()
     instance.buzzer()
-    expected = BUZZER + six.int2byte(2) + six.int2byte(4)
+    expected = BUZZER + bytes((2, 4))
     assert instance.output == expected
 
 
@@ -26,10 +25,10 @@ def test_buzzer_function_with_default_params():
         [9, 9],
     ],
 )
-def test_buzzer_function(times, duration):
+def test_buzzer_function(times: int, duration: int) -> None:
     instance = printer.Dummy()
     instance.buzzer(times, duration)
-    expected = BUZZER + six.int2byte(times) + six.int2byte(duration)
+    expected = BUZZER + bytes((times, duration))
     assert instance.output == expected
 
 
@@ -46,7 +45,9 @@ def test_buzzer_function(times, duration):
         [3, 11, "duration must be between 1 and 9"],
     ],
 )
-def test_buzzer_fuction_with_outrange_values(times, duration, expected_message):
+def test_buzzer_fuction_with_outrange_values(
+    times: int, duration: int, expected_message: str
+) -> None:
     instance = printer.Dummy()
     with pytest.raises(ValueError) as e:
         instance.buzzer(times, duration)
diff --git a/test/test_function_image.py b/test/test_function_image.py
index 981d536..c4b31a5 100644
--- a/test/test_function_image.py
+++ b/test/test_function_image.py
@@ -16,7 +16,7 @@ from escpos.exceptions import ImageWidthError
 
 
 # Raster format print
-def test_bit_image_black():
+def test_bit_image_black() -> None:
     """
     Test printing solid black bit image (raster)
     """
@@ -30,7 +30,7 @@ def test_bit_image_black():
     assert instance.output == b"\x1dv0\x00\x01\x00\x01\x00\x80"
 
 
-def test_bit_image_white():
+def test_bit_image_white() -> None:
     """
     Test printing solid white bit image (raster)
     """
@@ -39,7 +39,7 @@ def test_bit_image_white():
     assert instance.output == b"\x1dv0\x00\x01\x00\x01\x00\x00"
 
 
-def test_bit_image_both():
+def test_bit_image_both() -> None:
     """
     Test printing black/white bit image (raster)
     """
@@ -58,7 +58,7 @@ def test_bit_image_transparent():
 
 
 # Column format print
-def test_bit_image_colfmt_black():
+def test_bit_image_colfmt_black() -> None:
     """
     Test printing solid black bit image (column format)
     """
@@ -67,7 +67,7 @@ def test_bit_image_colfmt_black():
     assert instance.output == b"\x1b3\x10\x1b*!\x01\x00\x80\x00\x00\x0a\x1b2"
 
 
-def test_bit_image_colfmt_white():
+def test_bit_image_colfmt_white() -> None:
     """
     Test printing solid white bit image (column format)
     """
@@ -76,7 +76,7 @@ def test_bit_image_colfmt_white():
     assert instance.output == b"\x1b3\x10\x1b*!\x01\x00\x00\x00\x00\x0a\x1b2"
 
 
-def test_bit_image_colfmt_both():
+def test_bit_image_colfmt_both() -> None:
     """
     Test printing black/white bit image (column format)
     """
@@ -87,7 +87,7 @@ def test_bit_image_colfmt_both():
     )
 
 
-def test_bit_image_colfmt_transparent():
+def test_bit_image_colfmt_transparent() -> None:
     """
     Test printing black/transparent bit image (column format)
     """
@@ -99,7 +99,7 @@ def test_bit_image_colfmt_transparent():
 
 
 # Graphics print
-def test_graphics_black():
+def test_graphics_black() -> None:
     """
     Test printing solid black graphics
     """
@@ -111,7 +111,7 @@ def test_graphics_black():
     )
 
 
-def test_graphics_white():
+def test_graphics_white() -> None:
     """
     Test printing solid white graphics
     """
@@ -123,7 +123,7 @@ def test_graphics_white():
     )
 
 
-def test_graphics_both():
+def test_graphics_both() -> None:
     """
     Test printing black/white graphics
     """
@@ -135,7 +135,7 @@ def test_graphics_both():
     )
 
 
-def test_graphics_transparent():
+def test_graphics_transparent() -> None:
     """
     Test printing black/transparent graphics
     """
@@ -147,7 +147,7 @@ def test_graphics_transparent():
     )
 
 
-def test_large_graphics():
+def test_large_graphics() -> None:
     """
     Test whether 'large' graphics that induce a fragmentation are handled correctly.
     """
@@ -162,13 +162,13 @@ def test_large_graphics():
 
 
 @pytest.fixture
-def dummy_with_width():
+def dummy_with_width() -> printer.Dummy:
     instance = printer.Dummy()
     instance.profile.profile_data = {"media": {"width": {"pixels": 384}}}
     return instance
 
 
-def test_width_too_large(dummy_with_width):
+def test_width_too_large(dummy_with_width: printer.Dummy) -> None:
     """
     Test printing an image that is too large in width.
     """
@@ -180,7 +180,7 @@ def test_width_too_large(dummy_with_width):
     instance.image(Image.new("RGB", (384, 200)))
 
 
-def test_center_image(dummy_with_width):
+def test_center_image(dummy_with_width: printer.Dummy) -> None:
     instance = dummy_with_width
 
     with pytest.raises(ImageWidthError):
diff --git a/test/test_function_linedisplay.py b/test/test_function_linedisplay.py
index 693706c..4b05761 100644
--- a/test/test_function_linedisplay.py
+++ b/test/test_function_linedisplay.py
@@ -11,21 +11,21 @@
 import escpos.printer as printer
 
 
-def test_function_linedisplay_select_on():
+def test_function_linedisplay_select_on() -> None:
     """test the linedisplay_select function (activate)"""
     instance = printer.Dummy()
     instance.linedisplay_select(select_display=True)
     assert instance.output == b"\x1B\x3D\x02"
 
 
-def test_function_linedisplay_select_off():
+def test_function_linedisplay_select_off() -> None:
     """test the linedisplay_select function (deactivate)"""
     instance = printer.Dummy()
     instance.linedisplay_select(select_display=False)
     assert instance.output == b"\x1B\x3D\x01"
 
 
-def test_function_linedisplay_clear():
+def test_function_linedisplay_clear() -> None:
     """test the linedisplay_clear function"""
     instance = printer.Dummy()
     instance.linedisplay_clear()
diff --git a/test/test_function_set.py b/test/test_function_set.py
index 90458f3..482631b 100644
--- a/test/test_function_set.py
+++ b/test/test_function_set.py
@@ -1,12 +1,13 @@
 import pytest
 import six
+from typing import Optional
 
 import escpos.printer as printer
 from escpos.constants import SET_FONT, TXT_NORMAL, TXT_SIZE, TXT_STYLE
 from escpos.exceptions import SetVariableError
 
 
-def test_default_values_with_default():
+def test_default_values_with_default() -> None:
     """Default test, please copy and paste this block to test set method calls"""
     instance = printer.Dummy()
     instance.set_with_default()
@@ -26,7 +27,7 @@ def test_default_values_with_default():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_default_values():
+def test_default_values() -> None:
     """Default test"""
     instance = printer.Dummy()
     instance.set()
@@ -37,7 +38,7 @@ def test_default_values():
 # Size tests
 
 
-def test_set_size_2h():
+def test_set_size_2h() -> None:
     instance = printer.Dummy()
     instance.set_with_default(double_height=True)
 
@@ -56,7 +57,7 @@ def test_set_size_2h():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_size_2h_no_default():
+def test_set_size_2h_no_default() -> None:
     instance = printer.Dummy()
     instance.set(double_height=True)
 
@@ -68,7 +69,7 @@ def test_set_size_2h_no_default():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_size_2w():
+def test_set_size_2w() -> None:
     instance = printer.Dummy()
     instance.set_with_default(double_width=True)
 
@@ -87,7 +88,7 @@ def test_set_size_2w():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_size_2w_no_default():
+def test_set_size_2w_no_default() -> None:
     instance = printer.Dummy()
     instance.set(double_width=True)
 
@@ -99,7 +100,7 @@ def test_set_size_2w_no_default():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_size_2x():
+def test_set_size_2x() -> None:
     instance = printer.Dummy()
     instance.set_with_default(double_height=True, double_width=True)
 
@@ -118,7 +119,7 @@ def test_set_size_2x():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_size_2x_no_default():
+def test_set_size_2x_no_default() -> None:
     instance = printer.Dummy()
     instance.set(double_width=True, double_height=True)
 
@@ -130,7 +131,7 @@ def test_set_size_2x_no_default():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_size_custom():
+def test_set_size_custom() -> None:
     instance = printer.Dummy()
     instance.set_with_default(custom_size=True, width=8, height=7)
 
@@ -151,7 +152,7 @@ def test_set_size_custom():
 
 @pytest.mark.parametrize("width", [1, 8])
 @pytest.mark.parametrize("height", [1, 8])
-def test_set_size_custom_no_default(width, height):
+def test_set_size_custom_no_default(width: int, height: int) -> None:
     instance = printer.Dummy()
     instance.set(custom_size=True, width=width, height=height)
 
@@ -165,7 +166,9 @@ def test_set_size_custom_no_default(width, height):
 
 @pytest.mark.parametrize("width", [None, 0, 9, 10, 4444])
 @pytest.mark.parametrize("height", [None, 0, 9, 10, 4444])
-def test_set_size_custom_invalid_input(width, height):
+def test_set_size_custom_invalid_input(
+    width: Optional[int], height: Optional[int]
+) -> None:
     instance = printer.Dummy()
     with pytest.raises(SetVariableError):
         instance.set(custom_size=True, width=width, height=height)
@@ -174,7 +177,7 @@ def test_set_size_custom_invalid_input(width, height):
 # Flip
 
 
-def test_set_flip():
+def test_set_flip() -> None:
     instance = printer.Dummy()
     instance.set_with_default(flip=True)
 
@@ -193,7 +196,7 @@ def test_set_flip():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_flip_no_default():
+def test_set_flip_no_default() -> None:
     instance = printer.Dummy()
     instance.set(flip=True)
 
@@ -205,7 +208,7 @@ def test_set_flip_no_default():
 # Smooth
 
 
-def test_smooth():
+def test_smooth() -> None:
     instance = printer.Dummy()
     instance.set_with_default(smooth=True)
 
@@ -227,7 +230,7 @@ def test_smooth():
 # Type
 
 
-def test_set_bold():
+def test_set_bold() -> None:
     instance = printer.Dummy()
     instance.set_with_default(bold=True)
 
@@ -246,7 +249,7 @@ def test_set_bold():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_underline():
+def test_set_underline() -> None:
     instance = printer.Dummy()
     instance.set_with_default(underline=1)
 
@@ -265,7 +268,7 @@ def test_set_underline():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_set_underline2():
+def test_set_underline2() -> None:
     instance = printer.Dummy()
     instance.set_with_default(underline=2)
 
@@ -287,7 +290,7 @@ def test_set_underline2():
 # Align
 
 
-def test_align_center():
+def test_align_center() -> None:
     instance = printer.Dummy()
     instance.set_with_default(align="center")
 
@@ -306,7 +309,7 @@ def test_align_center():
     assert instance.output == b"".join(expected_sequence)
 
 
-def test_align_right():
+def test_align_right() -> None:
     instance = printer.Dummy()
     instance.set_with_default(align="right")
 
@@ -328,7 +331,7 @@ def test_align_right():
 # Densities
 
 
-def test_densities():
+def test_densities() -> None:
     for density in range(8):
         instance = printer.Dummy()
         instance.set_with_default(density=density)
@@ -352,7 +355,7 @@ def test_densities():
 # Invert
 
 
-def test_invert():
+def test_invert() -> None:
     instance = printer.Dummy()
     instance.set_with_default(invert=True)
 
diff --git a/test/test_image.py b/test/test_image.py
index 258e4f1..7f121f7 100644
--- a/test/test_image.py
+++ b/test/test_image.py
@@ -7,11 +7,12 @@ converted to ESC/POS column & raster formats.
 :copyright: Copyright (c) 2016 `Michael Billington <michael.billington@gmail.com>`_
 :license: MIT
 """
+from typing import List
 
 from escpos.image import EscposImage
 
 
-def test_image_black():
+def test_image_black() -> None:
     """
     Test rendering solid black image
     """
@@ -19,7 +20,7 @@ def test_image_black():
         _load_and_check_img("canvas_black." + img_format, 1, 1, b"\x80", [b"\x80"])
 
 
-def test_image_black_transparent():
+def test_image_black_transparent() -> None:
     """
     Test rendering black/transparent image
     """
@@ -29,7 +30,7 @@ def test_image_black_transparent():
         )
 
 
-def test_image_black_white():
+def test_image_black_white() -> None:
     """
     Test rendering black/white image
     """
@@ -39,7 +40,7 @@ def test_image_black_white():
         )
 
 
-def test_image_white():
+def test_image_white() -> None:
     """
     Test rendering solid white image
     """
@@ -47,7 +48,7 @@ def test_image_white():
         _load_and_check_img("canvas_white." + img_format, 1, 1, b"\x00", [b"\x00"])
 
 
-def test_split():
+def test_split() -> None:
     """
     test whether the split-function works as expected
     """
@@ -62,12 +63,12 @@ def test_split():
 
 
 def _load_and_check_img(
-    filename,
-    width_expected,
-    height_expected,
-    raster_format_expected,
-    column_format_expected,
-):
+    filename: str,
+    width_expected: int,
+    height_expected: int,
+    raster_format_expected: bytes,
+    column_format_expected: List[bytes],
+) -> None:
     """
     Load an image, and test whether raster & column formatted output, sizes, etc match expectations.
     """