diff --git a/slither/core/slither_core.py b/slither/core/slither_core.py
index c42503ca9..a67c68bc6 100644
--- a/slither/core/slither_core.py
+++ b/slither/core/slither_core.py
@@ -7,7 +7,7 @@ import json
 import re
 import math
 from collections import defaultdict
-from typing import Optional, Dict, List, Set, Union
+from typing import Optional, Dict, List, Set, Union, Tuple
 
 from crytic_compile import CryticCompile
 
@@ -57,7 +57,7 @@ class SlitherCore(Context):
         self._contract_name_collisions = defaultdict(list)
         self._contract_with_missing_inheritance = set()
 
-        self._storage_layouts = {}
+        self._storage_layouts: Dict[str, Dict[str, Tuple[int, int]]] = {}
 
     ###################################################################################
     ###################################################################################
@@ -380,6 +380,6 @@ class SlitherCore(Context):
                 else:
                     offset += size
 
-    def storage_layout_of(self, contract, var):
+    def storage_layout_of(self, contract, var) -> Tuple[int, int]:
         return self._storage_layouts[contract.name][var.canonical_name]
     # endregion
diff --git a/slither/core/solidity_types/array_type.py b/slither/core/solidity_types/array_type.py
index aba611b8c..966d1b537 100644
--- a/slither/core/solidity_types/array_type.py
+++ b/slither/core/solidity_types/array_type.py
@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import Optional, Tuple
 
 from slither.core.expressions import Literal
 from slither.core.expressions.expression import Expression
@@ -38,7 +38,7 @@ class ArrayType(Type):
         return self._length_value
 
     @property
-    def storage_size(self):
+    def storage_size(self) -> Tuple[int, bool]:
         if self._length_value:
             elem_size, _ = self._type.storage_size
             return elem_size * int(self._length_value.value), True
diff --git a/slither/core/solidity_types/elementary_type.py b/slither/core/solidity_types/elementary_type.py
index 16c25e2f0..6f1d7a8b5 100644
--- a/slither/core/solidity_types/elementary_type.py
+++ b/slither/core/solidity_types/elementary_type.py
@@ -1,5 +1,5 @@
 import itertools
-from typing import Optional
+from typing import Optional, Tuple
 
 from slither.core.solidity_types.type import Type
 
@@ -173,7 +173,7 @@ class ElementaryType(Type):
         return None
 
     @property
-    def storage_size(self):
+    def storage_size(self) -> Tuple[int, bool]:
         if self._type == 'string' or self._type == 'bytes':
             return 32, True
 
diff --git a/slither/core/solidity_types/function_type.py b/slither/core/solidity_types/function_type.py
index a666a3521..6a96bf368 100644
--- a/slither/core/solidity_types/function_type.py
+++ b/slither/core/solidity_types/function_type.py
@@ -1,4 +1,4 @@
-from typing import List
+from typing import List, Tuple
 
 from slither.core.solidity_types.type import Type
 from slither.core.variables.function_type_variable import FunctionTypeVariable
@@ -27,7 +27,7 @@ class FunctionType(Type):
         return [x.type for x in self.return_values]
 
     @property
-    def storage_size(self):
+    def storage_size(self) -> Tuple[int, bool]:
         return 24, False
 
     def __str__(self):
diff --git a/slither/core/solidity_types/mapping_type.py b/slither/core/solidity_types/mapping_type.py
index 815f2dd78..e2f8ebe30 100644
--- a/slither/core/solidity_types/mapping_type.py
+++ b/slither/core/solidity_types/mapping_type.py
@@ -1,3 +1,5 @@
+from typing import Tuple
+
 from slither.core.solidity_types.type import Type
 
 
@@ -18,7 +20,7 @@ class MappingType(Type):
         return self._to
 
     @property
-    def storage_size(self):
+    def storage_size(self) -> Tuple[int, bool]:
         return 32, True
 
     def __str__(self):
diff --git a/slither/core/solidity_types/user_defined_type.py b/slither/core/solidity_types/user_defined_type.py
index dc3c1dd8c..4aed394e8 100644
--- a/slither/core/solidity_types/user_defined_type.py
+++ b/slither/core/solidity_types/user_defined_type.py
@@ -1,4 +1,4 @@
-from typing import Union, TYPE_CHECKING
+from typing import Union, TYPE_CHECKING, Tuple
 import math
 
 from slither.core.solidity_types.type import Type
@@ -24,7 +24,7 @@ class UserDefinedType(Type):
         return self._type
 
     @property
-    def storage_size(self):
+    def storage_size(self) -> Tuple[int, bool]:
         from slither.core.declarations.structure import Structure
         from slither.core.declarations.enum import Enum
         from slither.core.declarations.contract import Contract