diff --git a/amaranth/lib/wiring.py b/amaranth/lib/wiring.py
index 1122a625f..c1004b869 100644
--- a/amaranth/lib/wiring.py
+++ b/amaranth/lib/wiring.py
@@ -1002,7 +1002,7 @@ def annotations(self, obj, /):
         return tuple()
 
     def __repr__(self):
-        if type(self) is Signature:
+        if isinstance(self, Signature):
             return f"Signature({dict(self.members.items())})"
         return super().__repr__()