diff --git a/src/packaging/specifiers.py b/src/packaging/specifiers.py
index 8be25a395..fb5811fa0 100644
--- a/src/packaging/specifiers.py
+++ b/src/packaging/specifiers.py
@@ -271,7 +271,7 @@ def prereleases(self) -> bool:
         return False
 
     @prereleases.setter
-    def prereleases(self, value: bool) -> None:
+    def prereleases(self, value: bool | None) -> None:
         self._prereleases = value
 
     @property
@@ -735,7 +735,7 @@ def prereleases(self) -> bool | None:
         return None
 
     @prereleases.setter
-    def prereleases(self, value: bool) -> None:
+    def prereleases(self, value: bool | None) -> None:
         self._prereleases = value
 
     def __repr__(self) -> str: