diff --git a/colour.py b/colour.py
index 9821684..ca8b2b7 100644
--- a/colour.py
+++ b/colour.py
@@ -50,7 +50,10 @@ class ColourValue(str):
         else:
             name = ""
 
-        return name  # ty:ignore[invalid-return-type]
+        assert isinstance(name, str), \
+            TypeError(f"`name` should be an instance of `str` not `{type(name)}`")
+
+        return name
     
     @property
     def hex(self) -> str: