diff --git a/openfisca_core/populations/_core_population.py b/openfisca_core/populations/_core_population.py
index cead5687b..0f0d968ce 100644
--- a/openfisca_core/populations/_core_population.py
+++ b/openfisca_core/populations/_core_population.py
@@ -28,7 +28,7 @@ class CorePopulation:
     """Base class to build populations from.
 
     Args:
-        entity: The :class:`.CoreEntity` of the population.
+        entity: The :class:`~entities.CoreEntity` of the population.
         *__args: Variable length argument list.
         **__kwds: Arbitrary keyword arguments.
 
@@ -43,7 +43,7 @@ class CorePopulation:
     #: A pseudo index for the members of the population.
     ids: Sequence[str] = []
 
-    #: The :class:`.Simulation` for which the population is calculated.
+    #: The :class:`~simulations.Simulation` for which the population is calculated.
     simulation: None | t.Simulation = None
 
     #: The holders of the variables.
@@ -67,7 +67,7 @@ def __call__(
             options: The options to use for the calculation.
 
         Returns:
-            None: If there is no :class:`.Simulation`.
+            None: If there is no :class:`~simulations.Simulation`.
             ndarray[generic]: The result of the calculation.
 
         Raises:
diff --git a/openfisca_core/populations/_errors.py b/openfisca_core/populations/_errors.py
index a8c64916f..69bda1a5a 100644
--- a/openfisca_core/populations/_errors.py
+++ b/openfisca_core/populations/_errors.py
@@ -1,11 +1,13 @@
 from openfisca_core import types as t
 
+from ._enums import Option
+
 
 class IncompatibleOptionsError(ValueError):
     """Raised when two options are incompatible."""
 
     def __init__(self, variable_name: t.VariableName) -> None:
-        add, divide = t.Option
+        add, divide = Option
         msg = (
             f"Options {add} and {divide} are incompatible (trying to compute "
             f"variable {variable_name})."
diff --git a/openfisca_core/reforms/reform.py b/openfisca_core/reforms/reform.py
index 76e715233..1f0b0ed38 100644
--- a/openfisca_core/reforms/reform.py
+++ b/openfisca_core/reforms/reform.py
@@ -71,7 +71,8 @@ def modify_parameters(self, modifier_function):
         Call this function in `apply()` if the reform asks for legislation parameter modifications.
 
         Args:
-            modifier_function: A function that takes a :obj:`.ParameterNode` and should return an object of the same type.
+            modifier_function: A function that takes a :obj:`~parameters.ParameterNode` and should return an object of
+            the same type.
 
         """
         baseline_parameters = self.baseline.parameters
diff --git a/openfisca_core/types.py b/openfisca_core/types.py
index 66b602057..01992ec40 100644
--- a/openfisca_core/types.py
+++ b/openfisca_core/types.py
@@ -406,15 +406,12 @@ def offset(
 #: Type alias for a period-like object.
 PeriodLike: TypeAlias = Union[Period, PeriodStr, PeriodInt]
 
+
 # Populations
 
 #: Type alias for a population's holders.
 HolderByVariable: TypeAlias = MutableMapping["VariableName", Holder[_N]]
 
-# TODO(Mauko Quiroga-Alvarado): I'm not sure if this type alias is correct.
-# https://openfisca.org/doc/coding-the-legislation/50_entities.html
-Members: TypeAlias = Iterable["SinglePopulation"]
-
 
 class MemoryUsageByVariable(TypedDict, total=False):
     by_variable: dict[VariableName, MemoryUsage]
@@ -448,6 +445,11 @@ def members_entity_id(self, /) -> StrArray: ...
     def nb_persons(self, /, __role: None | Role = ...) -> int: ...
 
 
+# TODO(Mauko Quiroga-Alvarado): I'm not sure if this type alias is correct.
+# https://openfisca.org/doc/coding-the-legislation/50_entities.html
+Members: TypeAlias = Iterable[SinglePopulation]
+
+
 # Simulations