1 files changed, 5 insertions, 3 deletions
diff --git a/Lib/functools.py b/Lib/functools.py
index 28d9f6f75f..c863341eec 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -861,9 +861,11 @@ def singledispatch(func):
             # only import typing if annotation parsing is necessary
             from typing import get_type_hints
             argname, cls = next(iter(get_type_hints(func).items()))
-            assert isinstance(cls, type), (
-                f"Invalid annotation for {argname!r}. {cls!r} is not a class."
-            )
+            if not isinstance(cls, type):
+                raise TypeError(
+                    f"Invalid annotation for {argname!r}. "
+                    f"{cls!r} is not a class."
+                )
         registry[cls] = func
         if cache_token is None and hasattr(cls, '__abstractmethods__'):
             cache_token = get_cache_token()