diff --git a/ptpython/signatures.py b/ptpython/signatures.py
index 228b99b2..8256f707 100644
--- a/ptpython/signatures.py
+++ b/ptpython/signatures.py
@@ -84,10 +84,13 @@ def from_inspect_signature(
     ) -> "Signature":
         parameters = []
 
-        def get_annotation_name(annotation: object) -> str:
+        def get_annotation_name(annotation: object) -> None:
             """
             Get annotation as string from inspect signature.
             """
+            if annotation == inspect.Parameter.empty:
+                return None
+
             try:
                 # In case the annotation is a class like "int", "float", ...
                 return str(annotation.__name__)  # type: ignore