diff --git a/hypothesis-python/src/hypothesis/internal/conjecture/junkdrawer.py b/hypothesis-python/src/hypothesis/internal/conjecture/junkdrawer.py
index b246885107..71e2546336 100644
--- a/hypothesis-python/src/hypothesis/internal/conjecture/junkdrawer.py
+++ b/hypothesis-python/src/hypothesis/internal/conjecture/junkdrawer.py
@@ -203,13 +203,11 @@ class LazySequenceCopy:
     in O(1) time. The full list API is not supported yet but there's no reason
     in principle it couldn't be."""
 
-    __mask: Optional[Dict[int, int]]
-
     def __init__(self, values: Sequence[int]):
         self.__values = values
         self.__len = len(values)
-        self.__mask = None
-        self.__popped_indices = None
+        self.__mask: Optional[Dict[int, int]] = None
+        self.__popped_indices: Optional[SortedList] = None
 
     def __len__(self) -> int:
         if self.__popped_indices is None: