diff --git a/src/Reactant/Models/Reactant.php b/src/Reactant/Models/Reactant.php
index 11cd8e5..5f2cecf 100755
--- a/src/Reactant/Models/Reactant.php
+++ b/src/Reactant/Models/Reactant.php
@@ -18,8 +18,10 @@
 use I\Love\Reactant\ReactionTotal\Models\ReactionTotal;
 use I\Love\Reacter\Models\Reacter;
 use I\Love\ReactionType\Models\ReactionType;
+use I\Love\Support\Object\Nullable;
 
-interface Reactant
+interface Reactant extends
+    Nullable
 {
     public function getId(): string;
 
@@ -47,10 +49,6 @@ public function isEqualTo(self $that): bool;
 
     public function isNotEqualTo(self $that): bool;
 
-    public function isNull(): bool;
-
-    public function isNotNull(): bool;
-
     public function createReactionCounterOfType(ReactionType $type): void;
 
     public function createReactionTotal(): void;
diff --git a/src/Reactant/ReactionCounter/Models/ReactionCounter.php b/src/Reactant/ReactionCounter/Models/ReactionCounter.php
index 57d9308..5a92a00 100755
--- a/src/Reactant/ReactionCounter/Models/ReactionCounter.php
+++ b/src/Reactant/ReactionCounter/Models/ReactionCounter.php
@@ -15,8 +15,12 @@
 
 use I\Love\Reactant\Models\Reactant;
 use I\Love\ReactionType\Models\ReactionType;
+use I\Love\Support\Object\Countable;
+use I\Love\Support\Object\Weightable;
 
-interface ReactionCounter
+interface ReactionCounter extends
+    Countable,
+    Weightable
 {
     public function getReactant(): Reactant;
 
@@ -25,16 +29,4 @@ public function getReactionType(): ReactionType;
     public function isReactionOfType(ReactionType $type): bool;
 
     public function isNotReactionOfType(ReactionType $type): bool;
-
-    public function getCount(): int;
-
-    public function getWeight(): float;
-
-    public function incrementCount(int $amount): void;
-
-    public function decrementCount(int $amount): void;
-
-    public function incrementWeight(float $amount): void;
-
-    public function decrementWeight(float $amount): void;
 }
diff --git a/src/Reactant/ReactionTotal/Models/ReactionTotal.php b/src/Reactant/ReactionTotal/Models/ReactionTotal.php
index 8bcfc88..308b9bc 100755
--- a/src/Reactant/ReactionTotal/Models/ReactionTotal.php
+++ b/src/Reactant/ReactionTotal/Models/ReactionTotal.php
@@ -14,20 +14,12 @@
 namespace I\Love\Reactant\ReactionTotal\Models;
 
 use I\Love\Reactant\Models\Reactant;
+use I\Love\Support\Object\Countable;
+use I\Love\Support\Object\Weightable;
 
-interface ReactionTotal
+interface ReactionTotal extends
+    Countable,
+    Weightable
 {
     public function getReactant(): Reactant;
-
-    public function getCount(): int;
-
-    public function getWeight(): float;
-
-    public function incrementCount(int $amount): void;
-
-    public function decrementCount(int $amount): void;
-
-    public function incrementWeight(float $amount): void;
-
-    public function decrementWeight(float $amount): void;
 }
diff --git a/src/Reacter/Models/Reacter.php b/src/Reacter/Models/Reacter.php
index 00c8d18..f1e8a5d 100755
--- a/src/Reacter/Models/Reacter.php
+++ b/src/Reacter/Models/Reacter.php
@@ -16,8 +16,10 @@
 use I\Love\Reactant\Models\Reactant;
 use I\Love\Reacterable\Models\Reacterable;
 use I\Love\ReactionType\Models\ReactionType;
+use I\Love\Support\Object\Nullable;
 
-interface Reacter
+interface Reacter extends
+    Nullable
 {
     public function getId(): string;
 
@@ -39,8 +41,4 @@ public function hasNotReactedTo(Reactant $reactant, ?ReactionType $reactionType
     public function isEqualTo(self $that): bool;
 
     public function isNotEqualTo(self $that): bool;
-
-    public function isNull(): bool;
-
-    public function isNotNull(): bool;
 }
diff --git a/src/Support/Object/Countable.php b/src/Support/Object/Countable.php
new file mode 100644
index 0000000..2856f0a
--- /dev/null
+++ b/src/Support/Object/Countable.php
@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of PHP I: Love.
+ *
+ * (c) Anton Komarev <anton@komarev.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace I\Love\Support\Object;
+
+interface Countable
+{
+    public function getCount(): int;
+
+    public function incrementCount(int $amount): void;
+
+    public function decrementCount(int $amount): void;
+}
diff --git a/src/Support/Object/Nullable.php b/src/Support/Object/Nullable.php
new file mode 100644
index 0000000..b7ece5b
--- /dev/null
+++ b/src/Support/Object/Nullable.php
@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of PHP I: Love.
+ *
+ * (c) Anton Komarev <anton@komarev.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace I\Love\Support\Object;
+
+interface Nullable
+{
+    public function isNull(): bool;
+
+    public function isNotNull(): bool;
+}
diff --git a/src/Support/Object/Weightable.php b/src/Support/Object/Weightable.php
new file mode 100644
index 0000000..c63a790
--- /dev/null
+++ b/src/Support/Object/Weightable.php
@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of PHP I: Love.
+ *
+ * (c) Anton Komarev <anton@komarev.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace I\Love\Support\Object;
+
+interface Weightable
+{
+    public function getWeight(): float;
+
+    public function incrementWeight(float $amount): void;
+
+    public function decrementWeight(float $amount): void;
+}