diff --git a/src/truststore/_api.py b/src/truststore/_api.py
index 189c393..98beef1 100644
--- a/src/truststore/_api.py
+++ b/src/truststore/_api.py
@@ -180,8 +180,8 @@ def set_alpn_protocols(self, alpn_protocols: typing.Iterable[str]) -> None:
     def set_npn_protocols(self, npn_protocols: typing.Iterable[str]) -> None:
         return self._ctx.set_npn_protocols(npn_protocols)
 
-    def set_ciphers(self, __cipherlist: str) -> None:
-        return self._ctx.set_ciphers(__cipherlist)
+    def set_ciphers(self, cipherlist: str, /) -> None:
+        return self._ctx.set_ciphers(cipherlist)
 
     def get_ciphers(self) -> typing.Any:
         return self._ctx.get_ciphers()