diff --git a/colorhash/cli.py b/colorhash/cli.py
index 57ca02f..b8c5f07 100644
--- a/colorhash/cli.py
+++ b/colorhash/cli.py
@@ -8,7 +8,7 @@ import textwrap
 from .colorizer import PaletteColorizer
 from .matricizer import Matricizer, NibbleMatricizer, RandomartMatricizer
 from .palettes import Palette, DEFAULT_PALETTES, PALETTES
-from .writer import ANSIWriter, SVGWriter
+from .writer import ANSIWriter, SVGWriter, Writer
 
 
 # TODO - WASM compile for embedding directly in HTML
diff --git a/colorhash/color.py b/colorhash/color.py
index 2248410..4af4e11 100644
--- a/colorhash/color.py
+++ b/colorhash/color.py
@@ -10,6 +10,7 @@ class Color(metaclass=abc.ABCMeta):
     This can be used to convert any color format into another color format.
     """
 
+    @abc.abstractmethod
     def to_html_color(self) -> str:
         """
         Convert this color to an HTML color.
diff --git a/colorhash/palettes.py b/colorhash/palettes.py
index 7e14681..7403eb8 100644
--- a/colorhash/palettes.py
+++ b/colorhash/palettes.py
@@ -6,7 +6,7 @@ from .color import Color, HSLColor
 
 
 HSLRange = range | float | int | list[float | int]
-Palette = Sequence[str]
+Palette = Sequence[Color]
 
 
 def quantize(r: range, steps: int = 16) -> list[float]: