diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 30afc24..49c7e07 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2665,9 +2665,9 @@
     {"__subclasses__", (PyCFunction)type_subclasses, METH_NOARGS,
      PyDoc_STR("__subclasses__() -> list of immediate subclasses")},
     {"__instancecheck__", type___instancecheck__, METH_O,
-     PyDoc_STR("__instancecheck__() -> check if an object is an instance")},
+     PyDoc_STR("__instancecheck__() -> bool\ncheck if an object is an instance")},
     {"__subclasscheck__", type___subclasscheck__, METH_O,
-     PyDoc_STR("__subclasscheck__() -> check if a class is a subclass")},
+     PyDoc_STR("__subclasscheck__() -> bool\ncheck if a class is a subclass")},
     {0}
 };
 
@@ -3490,7 +3490,7 @@
     {"__format__", object_format, METH_VARARGS,
      PyDoc_STR("default object formatter")},
     {"__sizeof__", object_sizeof, METH_NOARGS,
-     PyDoc_STR("__sizeof__() -> size of object in memory, in bytes")},
+     PyDoc_STR("__sizeof__() -> int\nsize of object in memory, in bytes")},
     {0}
 };