diff --git a/deal/_runtime/_decorators.py b/deal/_runtime/_decorators.py
index 099cd1d7..c04e54d1 100644
--- a/deal/_runtime/_decorators.py
+++ b/deal/_runtime/_decorators.py
@@ -172,10 +172,10 @@ def raises(
     """Decorator listing the exceptions which the function can raise.
 
     Implements [exception] contract.
-    If the function raises an exception not listed in the decorator,
+    If the function raises an exception not a subclass of the ones listed in the decorator,
     `RaisesContractError` will be raised.
 
-    :param exceptions: exceptions which the function can raise.
+    :param exceptions: exceptions which the function can raise, including their subclasses.
     :param message: error message for the exception raised on contract violation.
         No error message by default.
     :param exception: exception type to raise on the contract violation.
diff --git a/deal/_runtime/_validators.py b/deal/_runtime/_validators.py
index f2d3f4de..6a426cad 100644
--- a/deal/_runtime/_validators.py
+++ b/deal/_runtime/_validators.py
@@ -259,8 +259,9 @@ def _init(self, args: Args, kwargs: Kwargs, exc=None) -> None:
     def _validate(self, args: Args, kwargs: Kwargs, exc: Exception | None = None) -> None:
         assert exc is not None
         exc_type = type(exc)
-        if exc_type in self.exceptions:
-            return
+        for exception in self.exceptions:
+            if issubclass(exc_type, exception):
+                return
         raise self._exception() from exc_type